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How to Build a Computer?
By  Super Admin  | Published  11/21/2006 | How To Articles | Rating:
Choosing the parts

Before you jump onto the web and start spending lots of money on expensive computer parts, there are three important questions you should answer which will guide your purchases:

What will be the main function of the computer?
Will parts be available to use from your old computer--or do you want to reuse parts from your old computer?
How much can you afford to spend on the system?
Often, you will either want to hand your old computer down to someone else, in which case you must keep it functional, or it may be so old that you don't want to use any parts from it, because they will slow down your new machine too much.

What operating system am I going to use?
Before you buy components, be sure that they are supported by the operating system you plan to use. Almost all current, commonly available devices have drivers available for current versions of Windows (generally, anything 2000, XP or newer); if you want to run an alternative operating system, you'll have to do some research -- many alternatives have extensive 'Hardware Compatibility Lists'.

Windows hardware support lists
Windows XP supports most processors and motherboards based on the i386 or x86_64 architectures. Put simply, all available consumer processors (especially from AMD or Intel) will work with the Windows XP operating system.

For other hardware, see Microsoft's compatibility list.

Linux hardware support lists
As one of the most popular free operating systems, Linux is a very good alternative. It has versions for many different architectures, including i386, x64 and PowerPC, though i386 versions are much more common. It will also support all kinds of processors, enabling it to be used on Palm PCs and even iPods. There are many different versions of Linux, produced by different companies these are 'distributions' or 'distros' for short. For a desktop PC, you should make sure to pick a desktop distro, one where the company/organisation has desktop users in mind. e.g. Ubuntu, SimplyMEPIS, Mandriva. SUSE is also a good choice, but also has tools that make it easy to use as a server. Ubuntu has won many awards from PC magazines and is noted for being particularly easy to use (for basic tasks, i.e. Home/Office e.g. web, email, word processing)

All this is important to bear in mind as different distros will support different hardware (generally more 'bleeding-edge' distro will support newer hardware - look at Fedora, SuSE, Ubuntu, but not Debian). A good rule of thumb is to buy hardware that is 12 to 18 months old, as it most probably has Linux support with most distros, but won't be too old.


BSDs hardware support lists
DesktopBSD, see FreeBSD 5.4/i386 and FreeBSD 5.4/amd64
Dragonfly BSD
FreeBSD
NetBSD
OpenBSD
PC-BSD, see FreeBSD 6.0/i386

What will be the main function of the computer?
If you're going to build a computer from scratch for a specific purpose, you'll want to keep that purpose in mind when choosing your components; don't just go to the store or an online shop and start buying components. First, decide what you want to use the computer for. The reason you have to consider this is that you may be able to save money by only specifying expensive, premium components where needed.

Many differing speeds of computer can offer Internet browsing and word-processing capabilities; however, one computer might be faster than another at such tasks. For an office computer, the main components for speed are the processor, memory (RAM), system bus, and hard drive. If the computer is for gaming, the addition of a high-end graphics accelerator expansion card also becomes a major area which greatly affects computing performance and speed.

Simple web surfer
The most important tip is not to go overboard. Basic users can easily get by without the latest gadgets, and although it is easy to get caught up in the hype, you simply do not need to pay a significant amount of money for a computer intended for a new user. A computer used for web surfing and writing the occasional letter does not need to be powerful in any sense, as the speed-limiting steps are invariably the Internet connection speed and the speed at which you can type.
A worthwhile addition to any computer is a basic printer; printed webpages are portable and can be used when the computer is turned off, whether it be a recipe for use in the kitchen or road directions for use in the car. Also, almost everyone will need to print and send letters at times.
A dial-up (56kbps) modem is more than adequate for web browsing, but for users who want to do a lot of web browsing and dowloading large files, a faster modem such as DSL or cable might be preferable.
Server 
If you are going to use your computer as a server (for a lot of clients) you will need to buy lots of RAM, fast hard drives, one or more processors or processor cores, and good network hardware. Graphics and sound are not important. Servers are more availably used in businesses for remote access from clients and kiosks.
Office computer 
For an office computer, you will not need much in the way of graphics or computational power, but you will want to spend more money on interface devices, such as an ergonomic keyboard, a nicer printer, and a larger monitor with a sharp picture, since you may be spending a lot of time using the computer and having to stare at the screen for long periods of time. Also invest in productivity software and a client edition of your operating system (if working from a remote location).
Gaming computer 
On the other hand, somebody who is going to be playing the latest games on their new computer is going to need a lot more graphics power. A powerful graphics card from nVidia or ATI is practically a must. A fast gaming processor such as the Athlon 64 line or Core 2 Duo would be very useful, too. However, they may not want to spend much on computer peripherals such as scanners, printers, or webcameras because they have no interest in such devices. Most newer games require anywhere from 1GB to 4GB of RAM. A DSL or cable internet connection is a necessity for multiplayer gaming - even if you have the fastest computer in the world, a slow internet connection will make it useless for internet gaming.
Workstation 
Some may be more interested in processing large amounts of data. For instance, processing video, rendering, or running computer simulations. In this case the focus is primarily on CPU speed and a common choice is dual CPUs or CPU cores. Gobs of memory is secondary, and a fine RAID hard drive setup can be helpful. Choosing a good motherboard is critical. As is choosing the right amount of RAM (Random Access Memory). Depending on the application, you may need a decent video card. However, most workstation applications will work fine on a value-line video card, since they usually use fairly simple graphics compared to video games. For specific video applications, a video card with specific features may be needed.
Entertainment system 
Here, you'll be most interested in a silent, good-looking case design and, of course, a good monitor. There's a good chance you want to use it as a Personal Video Recorder (PVR) in which case, TV tuner cards, either integrated with the video card or separate, should be selected wisely.

Do I plan on overclocking my computer?
Overclocking is running components of a computer at faster internal speeds than those for which the components were designed. If you plan to overclock your components, some parts respond to overclocking better than others. If you are going to seriously overclock your computer, you need to do extensive research into the components you are selecting. Components that respond well to heavy overclocking are generally not very expensive, although the price of a component is by no means a guarantee of its overclocking potential. It is also important to check your warranties before overclocking. Overclocking sometimes voids your warranty. Overclocking is very risky (you can destroy your entire computer), so be warned! You need to make considerations for cooling the computer as overclocking generates heat. Anything from a few extra fans to a liquid-cooled system may be necessary depending on the nature of your system.

Do I plan on underclocking my computer?
This can be ideal for always-on entertainment systems. Similar considerations as mentioned above for selecting tweakable components. Underclocking allows passive cooling to be used on the underclocked components and results in a silent and energy-efficient system.

The risk here is not destroying your computer, as with overclocking, but instead you may experience problems with hard-disk data integrity. It is a good idea to back up your disk data periodically on a non-volatile medium, such as DVDs or tape.

Can I use any of the parts from my old computer?
The answer to this question is unique in nearly every situation. To start, is your old computer available to take spare parts out of? There are usually several reasons why it wouldn't be.

You want to sell, donate, or give the old machine to a family member.
You want to use your old computer for another use, such as using it as a server of some sort.
Your old computer is too old, or the parts which you wish to reuse are broken, and so will be of no use.
A lot of parts are incompatible with the new computer
In the first situation, you want to sell the old computer. In order to do this, you need to leave in enough parts in order for the computer to function correctly. These include: graphics card (if it's not on the motherboard), hard drive, motherboard, processor, power supply and RAM. However, it is usually a kind gesture to leave, at least, a rudimentary sound card and an ethernet card so the person you are selling your computer to can use a network and play sound and music. Other than these basic parts, you can use the other parts for your new computer if they meet the other criteria above. One important point to remember is that if you are selling your old computer, it is generally a wise idea to erase the hard drive before giving it to it's new owner. Special precautions must be taken to ensure that you are not giving away your sensitive or personal information when you sell your computer. Don't forget that a simple 'delete' command does not actually erase the data on your hard drive. The original data will still be present and can later be recovered by someone else using special programs and/or equipment. To avoid this, programs are available that will effectively 'shred' your data, making it unrecoverable.

Along with using some parts if you are selling a computer, you can also use non-vital parts if you want to use the old computer as a server. For example, if you plan to reuse your old computer as a utility server, you can easily remove parts such as external drives and the sound card, as these have no use in a server, and they can easily be reused in your new computer, if they are of good enough quality and sufficient performance.

Another important fact to remember is that sometimes you may not be able to use old parts because they do not work with your new computer. For example, even if you recently upgraded to a very fast AGP card, if your new motherboard has a PCI-Express 16x slot, you will have to get a new graphics card, as the old card simply won't plug in to the available slot. RAM from your old computer will also often be unusable in your new motherboard.

Since monitor technology moves quite slowly, you can probably keep your current monitor and use it on the new computer, if it's of sufficient size and clarity for your work. The same can go for keyboards (unless you want to upgrade your keyboard to a better model), as well as mice, printers, scanners, and possibly speaker sets. On the inside, you may be able to take out the floppy drive, CD-ROM drive, and possibly the sound card and hard drive (depending on how good they are, of course). Sometimes so much is used from the old computer, that the line between an upgrade and a new computer can become very blurred.

Reusing a hard drive from an older computer is an easy way to keep your data from your old computer, though, with most Windows operating systems, moving a boot drive from one motherboard to another will entail a series of reboots and installation of new drivers; in the case of newer Windows systems, like 2000 and XP, an entire 'refresh install' may be necessary, to allow Windows to install a new Hardware Abstraction Layer.

Where do I find the parts?
Once you have decided what you are going to primarily use your computer for, and you have reviewed which parts are available for reuse, you should make a list of what components you will need to actually build your computer. Always research the best components for your computer's application, and be sure on the exact specifications that you will need, as this will save a lot of time and effort when you start shopping around. Make sure that you understand all terminology related to components before you purchase, as this can also save a lot of confusion later in the process.

There are several places to buy parts:

Internet retailers generally offer the best price for new parts. The main disadvantage occurs if a part is broken and requires returns.
Auction sites offer very good prices for used parts. This is especially useful for parts which do not wear out. As with internet retailers, returns can be problematic.
Local PC shops - Their prices are higher, but they make up for this by providing a lot of expertise.
Big local retailers often have low technical expertise and not very good prices, but are very useful because they can handle returns quickly.
Trade shows that occur from time to time also provide a good place to shop, as the prices are often significantly reduced.
Also, check your local town dump. They may have a special section for computers & monitors that others have gotten rid of. Many times these are more or less brand new computers with such trivial problems as a busted power supply or faulty cables. Of course if the dump does have such a section, it is wise to ask permission of those in charge. They're usually glad to let you go through it, but don't leave a mess. Taking advantage of this can yield incredible finds, with a price tag of free.

OEM vs retail
Most hardware manufacturers will sell the same components for both OEM and Retail computers. Retail hardware is intended to be sold to the end-user through retail channels, and will come fully packaged with manuals, accessories, software, etc. OEM stands for "original equipment manufacturer"; items labeled as such are sold in bulk and are intended for use by firms which may integrate the components into their own products.

However, many online stores will offer OEM hardware at cheaper prices than the corresponding retail versions. You will usually receive such an item by itself in an anti-static bag. It may or may not come with a manual or a CD containing drivers. Warranties on OEM parts may often be shorter, and sometimes require you to obtain support through your vendor, rather than the manufacturer. Other than that, OEM components themselves are usually the same as their retail counterparts.

What should affect the choice of any part/peripherial?
This section lists things that should be taken account of with every single choice when selecting parts. Considering some parts these things are more obvious than with others.

Compatibility
Do your parts and peripherials work together? The three main components that must work together are the CPU, the motherboard, and the RAM. Do they work with the software of your choice? Choosing parts that work with any other operating system than the most mainstream one is often a guarantee that they work with many other operating systems too than just those two. This is good because you can change your mind later. So even if you're building a computer to run Windows, choosing hardware that would run a Linux system might be a good thing. It is also worth checking round the internet to make sure there is no history of your chosen components clashing (eg Motherboards and Graphics cards).

Ergonomics
Ergonomics is most important when choosing peripherals such as keyboard or a mouse, but also the ease of assembly is important when choosing parts.

Ergonomics is the applied science of equipment design, as for the workplace, intended to maximize productivity by reducing operator fatigue and discomfort.

Operating temperature
The computer has to be cooled down so it doesn't overheat and break. Parts with high operating temperatures need more cooling and noiseless cooling is hard to find as well as being far more expensive than their noisy counterparts. Parts and peripherials with high operating temperatures also tend to warm up the room when the system is cooled by air, so the room may need cooling too. Manufacturers assume the computer will be kept in a room that has an air conditioner kept roughly at "room temperature" (≈73F or 22C) but, typically parts are expected to be able to handle more extreme conditions. More heat can tend to decrease stability and increase the elements that break down components slowly over time, so better cooling increases the stability as well as lifetime of your system. Since most of the energy used by a computer is turned into heat, you can tell how much heat a part is generating from the amount of power it consumes.

Price
In the early 80's, desktop computers as compared to modern models were slow, expensive, and mostly limited to businesses and computing hobbyists. However, as time went on, hardware speed and performance improved dramatically while prices steadily decreased. Today, there is a wide array of hardware core components and peripherals tailored to fit every home computing need and budget. Retail outlets, "big-box" electronic stores, and online warehouses offer everything from floppy drives to blazing-fast custom gaming systems built to buyer's specifications.

With all these options to choose from, it can be a bit overwhelming if you've never bought computer parts before. Shop around and compare the prices of both online and retail stores. Remember to factor in shipping and handling, and taxes. Some places may be priced a bit higher, but offer perks such as free shipping, limited warranties, or 24-hour tech support. Many websites, such as CNET and ZDNet offer comprehensive reviews, user ratings, and links to stores, including price comparisons. Although it may be tempting to buy the latest cutting-edge system with all the hottest bells and whistles, you may be able to save a considerable amount of money by purchasing a slightly older computer and upgrading it with a few high-quality peripherals.

Also, keep in mind that components are constantly improving in performance and becoming cheaper to produce, making them less expensive and more available to a wider consumer market. It may pay off to wait until the "hot item" you want comes down in price.

Most importantly, have a clear idea of what you want to use your computer for. It really doesn't make any sense to shell out $500 for a graphics card if you only need your computer for websurfing and email. In short, "Don't pay for features you don't need" is a good rule of thumb when you are shopping for parts.

It may well, however, pay you to think of future upgradeability when selecting some components, this is most true of the motherboard. While the computer that you are building today may be fine for your current needs you will probably need to upgrade it later to meet the ever expanding requirements of some software. So look for a motherboard that will allow you to fit more memory than you are planning to use, preferably without having to replace any of the existing memory. Also look for support for recent standards of connection to other equipment, e.g. you may be going to use a cheap IDE hard drive at the moment but later you will possibly need to upgrate to a larger, faster,SATA drive - so get a motherboard that supports both. It is always a good idea to have some spare slots for both memory and interface cards - if you are currently using all the facilities it is possible to fit to a machine the only possible upgrade is often another new machine.

You may also find that by overspecifing in some areas you can save money on others, e.g. if you don't currently need fantastic sound but you do need firewire then some of the higher end sound cards also have a firewire port.

Power
The speed of a processor, the size of memory, resolution of monitor, the output of cooling fans, printer or a scanner. Find out what is enough and look for the best price/quality-relation matching your need and budget.

Primary Components
These are the components that will be the core of your new computer. It is impractical to put together a PC compatible computer without these components and a bare set of peripherals.

Chassis (case) & power supply
The case was probably the most overlooked part of the whole computer at one stage. Most cases were beige, and since most components drew far less power than similar components do now, power supplies were never talked about. Recently, however, cases have become considerably more attractive, and people spend a sizable amount of their upgrade budgets on lights and glow-in-the-dark cables. Cases now come in millions of styles, and colours to suit anyone's taste.

People are spending more money on cases now than they ever have before. If you are only building an office computer, the style of case will be of little concern to you, so you might only want a inexpensive ATX case (ATX is the specification which makes them the same size, so you can put the same parts inside), and an inexpensive power supply, since you won't be running high-end processors or high-end graphic cards. Keep in mind not to buy a power supply with a sleeve bearing fan, as these are of considerably less quality. As a guide, you will not want a power supply with a rating of less than 300 watts, as you may likely not be able to power all the parts in your computer with a power supply with a lower rating. Most case-power supply bundles are adequate, but tend to be of a lower quality than power supplies that are sold separately from cases.

For a quiet system, you may want to choose a fanless power supply -- more expensive but well worth it if noise is a concern.

For cases and power supply there are 5 things to consider.

Formfactor
For general use, the ATX formfactor is recommended because it allows your computer to be easily expanded, and is the most common standard formfactor for computers.

ATX In this form factor the motherboard is vertical for more space and more efficient cooling.
Micro ATX is smaller than vanilla ATX, but at the cost of fewer expansion slots. Flex ATX is even smaller than Micro ATX, but only allows 2 expansion slots.
WTX is intended for workstations and servers.
BTX is another formfactor designed for more efficient cooling.
PicoBTX 8"x10.5"
'MicroBTX up to 10.4"x10.5"
BTX up to 12.8"x10.5"
Mini-ITX is even smaller than BTX, at 6.75" square.
NLX
Many OEM computers use non-standard formfactors. Be sure to choose a motherboard compatible with your case's formfactor.

Number of storage drive spaces
Internal hard drives/floppy drives (which go in the small 3.5" bays) and internal DVD drives (which go in the large 5.25" bays) take up space in the case, so make sure you consider how many drives you have. It is usually a good idea to calculate the number of drive spaces needed using your motherboard requirements as a baseline minimum.

Number of IDE x2
Number of FDD x2
Number of SATA
Number of SCSI2 (estimated)
e.g. For a motherboard with one FDD, one IDE, 4 SATA no SCSI. It is often best to choose one with at least 8 slots.
4 BIG + 4 SMALL = 4 optical drives + 3 hard drives + 1 floppy drive
This is the mid-tower configuration. For smaller computers with less storage drives, like 1 hard drive and 2 optical drives, get a mini-tower (2 BIG + 2 SMALL) because it saves space.

Note that it's possible to buy adaptors to fit items that go in small bays (usually hard drives) into large bays. It is however not possible to do the reverse.

Power rating
A too small power number doesn't run your high power devices (like optical, CPU and Graphics Cards). For certain graphics cards (especially high end ones with dual expansion slots), a recommendation of 450W is required. In general, if your motherboard has a 24 pin power connector, choose one which is at least 350W as the 4 extra pins are for high power applications. Also, you would want a PSU with dual 12 volt rails rated together for at least 30 amps. When in doubt, buy a more powerful PSU.

Choose an efficent PSU. Efficient PSU runs cool and quiet and thus do not cause much noise (important if you plan to sleep in the same room with it or using it as a media centre PC)

Note: Intel Pentium 4/D/EE have high power requirements, a 300W PSU is recommended.

Fan
Some cases have case fans. Make sure to choose one which matches your CPU interface on the motherboard. The best option is to purchase a 4-pin Molex connector fan as some motherboards do not have three pin fan ports. Although most motherboards fit most cases, it is the position of the case fan that affects speed and stability of the system. A good case has the fan aimed directly at the CPU for best results.

Aim to choose fans which are quiet. Usually larger fans run slower and produce less noise (and thus more efficient).

Aesthetics and power
If you plan on building a high end gaming PC, you might want a case that looks good, and a much more potent power supply. For the more aesthetically inclined, there are countless companies who make designer cases that will suit many personal preferences. A power supply with more than 400 watts is usually more than is required by most people, and will allow you to power high-end graphics cards, cooling systems, and aesthetic enhancements such as cold cathode lights, cooling equipment, and other such things.

In all cases you should try to check reviews from a computer hardware site before you decide to purchase a power supply; quality can vary greatly and wattage output is frequently overstated. Quality power is also usually more efficient, so it will produce less heat and its fans can run at lower, quieter speeds. Manufacturers sometimes try to make passive, or fanless, power supplies, but in most cases they will end up running dangerously hot, and so are only suitable if you plan to add your own cooling solution.

CPU (processor)
The Central Processing Unit (CPU) is the heart of your computer as it performs nearlly all functions that require extensive processing power. Therefore, it is very important that you choose a suitable CPU for your function as the choice of CPU directly affects the speed and stability of your system.

Before we can explain differences between CPUs, you must first be familiar with certain CPU properties.

Clock speed 
Clock speed, measured in Gigahertz (GHz), (or Megahertz (MHz) on older systems) is the number of calculation cycles that your CPU can perform per second. Therefore, a higher clock speed generally points toward a faster system. But not all CPUs perform an equal quantity of work per cycle, meaning two CPUs at the same clock speed can potentially perform at very different levels.
IPC 
IPC, or instructions per cycle, is the amount of work a CPU can do in a cycle. This varies with different properties of the CPU.
Front side bus speed (FSB) 
Front side bus speed is the rate at which the CPU communicates with the northbridge chipset component on your motherboard in MHz. A larger FSB value shows that your CPU is able to communicate with other components on the motherboard (and thus your system) faster.
Interface (Socket/Slot) 
CPUs must connect to motherboards via a series of connectors. It is VERY important that your CPU interface is a COMPLETE MATCH to your motherboard CPU socket otherwise you would be wasting money on a piece of spare silicon.
Bit-rate 
Most modern CPUs are of the 32-bit system which work fine with most modern operating system and hardware. Higher end models are the 64-bit system which may allow faster CPU processing capabilities due to the larger band-width, but not all operating systems are compatible with the newer 64-bit format -- they will still run, but without a major performance boost. You will require 64-bit if you require to manage more than 4GB of RAM.
Cores and Hyperthreading (HT):

Dual-Core Advantages
Dual-core processors are a fairly new innovation built by both major processor manufacturers (Intel Core Duo / Core 2 Duo and AMD Athlon 64 X2).

Multitasking: Each processor has two processing centres (cores) for (a theoretical maximum of) twice the operating power and for better multitasking. Major advantages of dual core processors are evident when doing heavy multitasking, such as encoding video and playing video games at the same time.
Application Support: Newer applications are being written to take advantage of this technology by using a technique known as Multithreading.
Power Saving: Dual core processors (especially Intel Core Duo) have the ability to turn off one of its cores when application demand is low to save power.

Disadvantages
Support: Older programs with certain notable exceptions) do not support multithreading and may run slower on dual core CPUs.
Price: Dual core processors are also significantly more expensive than their single core brethren

Multi-core Future?
However with quad core technology around the corner, and more and more programs being built to take advantage of multiple cores, the prices are sure to decrease, and the availability and usability of dual core processors is sure to increase greatly.

Hyper-threading (HT) 
Hyper-threading is a technology which allows a single core processor to simulate having two cores, giving a performance boost when running several programs at once. It requires motherboards and chipsets supporting Hyper-Threading technology. It also suffers similar disadvantages as Dual-Core Processors of support and price.
Cache 
Cache is the amount of Memory dedicated for the CPU in MB. Generally, the larger the cache, the faster your system would run. However, cache uses a lot of transistors, and the larger the cache, the higher number of transistors needed, which consume more electricity, and output more heat. Cache comes in (usually) three varieties, L1, L2, and L3. L1 being the smallest and fastest, and L3 being the largest and slowest. Usually only the L2 cache size will be shown, as L3 is rarely used in processor design, and L1 will often stay the same size throughout an entire processor product line.
Core 
The Core of the CPU is the heart of the CPU. Often several cores will be marketed under the same name, so look at what core you are buying.
Now, one of the most common mistakes of choosing a CPU is by ignoring the fine print of CPU specifications while relying completely on the clock speed. CPUs specs are written in full:

Intel Pentium 4 3.2GHz LGA775 FSB800 HT L2-2MB
Model: Intel Pentium 4
Clock Speed: 3.2GHz (=3200MHz)
Interface: Land Grid Array 775
L2-Cache: 2MB (=2048 kB)
Frontside Bus: 800 Mhz
Other Spec: HT technology
The consumer logic for processor speed may be misleading because many consumers think that clock speed, which is measured in gigahertz (GHz) or megahertz (MHz) is equal to system speed. While the higher the clock speed the CPU is able to do cycles more frequently and it does have a fundamental effect on speed, it is not the sole factor as the number of calculations per cycle is different for each different manufacturer and model.

Intel classifies its CPUs using a series of numbers. 3xx, 4xx, 5xx, 6xx and 7xx of which 7xx being the highest end products. Generally, the higher the number, the faster the CPU and the more expensive. usually, models and ratings correspond.

3xx Series: Intel Celeron (L2-128KB)
4xx Series: Intel Celeron D (L2-512KB)
5xx Series: Intel Pentium 4 / Celeron D (L2-1MB)
6xx Series: Intel Pentium 4 / Pentium 4 XE (L2-2MB)
7xx Series: Intel Pentium 4 XE
8xx Series: Intel Pentium D
9xx Series: Intel Pentium D
The number followed by suffix J signifies XD technology.

e.g. Intel Pentium 4 3.0GHz L2-1MB with HT --> Intel Pentium 4 530J
AMD CPUs are even more confusing in classification. The AMD Athlon CPU rating are not of the actual clock speed but rather the equivalence bench mark performance corresponding to a comparison to the AMD Athlon Thunderbird 1.0Ghz. The conversion Table is as follows:

AMD Athlon 1500+ = Actually runs at 1.33 GHz
AMD Athlon 1600+ = Actually runs at 1.40 GHz
AMD Athlon 1700+ = Actually runs at 1.47 GHz
AMD Athlon 1800+ = Actually runs at 1.53 GHz
AMD Athlon 1900+ = Actually runs at 1.60 GHz
AMD Athlon 2000+ = Actually runs at 1.67 GHz
AMD Athlon 2100+ = Actually runs at 1.73 GHz
AMD Athlon 2200+ = Actually runs at 1.80 GHz
AMD Athlon 2400+ = Actually runs at 1.93 GHz
AMD Athlon 2500+ = Actually runs at 1.833 GHz
AMD Athlon 2600+ = Actually runs at 2.133 GHz
AMD Athlon 2700+ = Actually runs at 2.17 GHz
AMD Athlon 2800+ = Actually runs at 2.083 GHz
AMD Athlon 3000+ = Actually runs at 2.167 GHz
AMD Athlon 3200+ = Actually runs at 2.20 GHz
You may wish to purchase a high end AMD64/EM64T (from Intel) processor, which provides support for 64-bit operating system (eg. Windows XP Professional 64-bit Edition). A 64-bit system is very efficient in handling large amounts of RAM. A 32-bit system efficiency drops beyond about 512 to 864MB of RAM, and becomes significantly less efficient beyond 4GB of RAM. Most processors for gaming range in about the 2.8Ghz-3.2Ghz

A 64-bit processor is currently an expensive investment as most applications run on the 32-bit system. However, there is no doubt that the 32-bit system would gradually be replaced by the 64-bit system when the prices fall over a few years time. It is unlikely that the 64-bit system would completely replace the 32-bit system within 5 years but Linux users might find a great improvement in speed when a 64-bit processor is used. Note that there are processors that can run 32-bit code and 64-bit code; they are becoming very popular and may prove a very wise investment for the future of computing, which will invariably be 64-bit. They are more expensive than processors that only run 32-bit code; however, it should be noted that AMD has invested in this market faithfully, and therefore all of their processors, even their low-end Sempron line, runs both types of code. The same cannot be said for the Intel family, which only includes such technology in their high-end server processors and the majority of their desktop line in what is called "EM64T", or Extended Memory 64 Bit Technology. This is an advantage to purchasing an AMD processor.

Smaller processors are generally preferred for overclocking, as they run cooler, and can achieve higher clock speeds. Retail CPU's come in a package containing a HSF (Heat Sink Fan), instructions, and a warranty, often 3 years. OEM CPUs do not include these.

The current CPU speeds and advantages change frequently, so for up-to-date comparisons, you may want to check a website that specializes in Hardware reviews, such as Tom's Hardware Guide or Anandtech. A current (as of 14 February 2006) beginner's explanation can be found at Behardware.

CPU cooling
CPU cooling is very important and should not be overlooked. A less than average CPU temperature prolongs CPU life (up to more than 10 years). On the other hand high CPU temperatures can cause unreliable operation, such as computer freezes, or slow operation. Extremely high temperatures can cause immediate CPU destruction by melting the materials in the chip and changing the physical shape of the sensitive transistors on the CPU. Because of this, never switch on the computer if your CPU has no cooling at all. It is an extremely stupid thing to do, the scenario of "I'll just test whether my CPU works!" as by doing so, you would find that the CPU fries in less than 5 seconds and you will be off to buy a new one.

Most CPU installations use forced-air cooling, but convection cooling and water cooling are also options. For traditional forced-air cooling, the heat sink and fan (HSF) included in most retail CPUs is usually sufficient to cool the CPU at stock speed. Overclockers might want to use a more powerful aftermarket fan, or even try water cooling because they need additional cooling ability given the increased heat of overclocking.

HSFs with decent performance are usually copper-based. The cooling effect is enhanced if the HSF has heatpipes. Silent (i.e. fanless) HSFs are there to provide users a nearly silent cooling.

Many retail heatsink+fan units have a thermal pad installed, which transfers heat from the CPU to the fan helping diffuse the heat created by the CPU. This pad is usable only once. If you wish to remove the fan from another CPU so that you can use it on your new one, or need to take it off for some reason, you will need to remove it, and apply a thermal paste or another thermal pad. Note that some of the cheaper pads can melt in unexpected heat and may cause problems and potentially even damage if you are overclocking. In either case, thermal paste is usually more effective, just harder to apply. If you plan to do any high performance computing, or removing and replacing the HSF, often thermal paste is suggested. If you are planning a long term installation a thermal pad is suggested. Non-conductive thermal pastes made up of silicon are the cheapest and safest.

Silver-based thermal pastes sometimes perform better than normal thermal pastes, and carbon-based ones perform better still. When applied improperly both can be conductive, causing electrical shorts upon contact with the motherboard. A thin properly-applied layer will usually prevent this problem, though some pastes can become runny when they get hot. Users should also beware that many "silver" thermal pastes do not actually contain any silver metal.

For quiet operation, start with a low-heat (low number of watts) CPU. Processors made by VIA, such as the VIA C3, tend to produce low amounts of heat. The Pentium M gives performance that is on par with many of the desktop processors, but gives off more heat than the Via processors. You can also underclock your CPU, giving up some unneeded performance for some peace and quiet. Another option is to choose a large copper heat sink with an open fin pattern. However, true fanless operation is difficult to achieve in most case designs. You can position a case fan to blow across the heat sink, or mount a fan on the heat sink. With either choice of fan placement, choose a large and slow fan over a small and fast fan to decrease noise and increase air flow.

Some low-noise CPU cooling fans require special mounting hardware on the motherboard. Be sure that the cooling fan you choose is compatible with your motherboard.

Motherboard
It cannot be over stressed that the motherboard is the MOST important part of your computer. It is worth investing in a decent motherboard rather than a CPU (although if financially acceptable, both) as your motherboard is what connects different parts of the computer together. In addition, the difference between a cheap and a quality motherboard is typically around $100. A good motherboard allows a modest CPU and RAM to run at maximum efficiency whereas a bad motherboard restricts high-end products to run only at modest levels. A high quality motherboard can go for $200 U.S. or more.

There are 6 things one must consider in choosing a motherboard, CPU Interface, Chipset, IDE or SATA support, Expansion Slot Interfaces and Other Connectors.

CPU Interface
The CPU interface is the "plug" that your processor goes into. For your processor to physically fit in the motherboard, the interface must be an exact match to your processor. Intel currently has two mainstream formats, the older Socket 478 (which is gradually being phased out) and the newer Land Grid Array 775, which supports higher end CPU with HT technology due to its more efficient transfer rate. AMD currently uses three sockets, AM2, 754 and 939. New AM2 sockets are faster (compatible with DDR II RAM) and more efficient than the older two. Socket 754 was aimed at the value market, while Socket 939 was for performance applications.

To ensure that the processor has the correct interface as the motherboard supports, the vendor would typically list this information on its specifications.

Formfactor
You must choose a case that your motherboard can fit inside of. A MicroATX motherboard will do, mostly because it can fit, and it fits many type of CPU sockets, while an ATX motherboard is also viable. Other choices such as MiniITX and NanoITX may also be considered for small form factor or home entertainment computers. The new BTX form factor may be used by enthusiasts. Note that much of the time, an ATX case can contain Micro-ATX motherboards.

Chipset
Chipsets are also important as it determines the efficiency of RAM and Expansion slots

Intel 915 supports up to 533MHz PC4200 DDRII RAM
Intel 925 supports up to 600MHz PC4800 DDRII RAM
All currently existing and in AMD formats currently use DDR RAM, with the standard 400MHz PC3200 being most common. Most Intel socket 478 processors also use the older DDR RAM

The functions of BIOS is highly important. Some BIOS features crash proof functions essential for updating the firmware. Other motherboards allow BIOS control of overclocking of CPU, RAM and Graphics card which are much more stable and safer for overclocking. Newer BIOS have temperature controls, and functions that shut down the computer if the temperature gets too high.

IDE (ATA) or SATA interface
Older PCs have the two IDE interface which are parallel 44 pin connectors but as the motherboard cannot access two devices connected on the same IDE port simultaneously, this has caused a drawback in speed of hard drives and DVD-drives. The newer serial ATA (SATA) interface has 4 separate slots that allow independent access and thus increases the speed of which hard drives work.

Expansion slot interfaces
Old motherboards may have one or more the following slots:

AGP - for graphics cards (ranging from AGP 1x, 2x, 4x and 8x)
PCI - for expansion cards and obsolete low end graphics cards
Note that some graphics cards that run on PCI interfaces are not always obsolete. ATI still manufactures PCI graphics cards, but for better performance try a card supporting PCI-Express. AGP is not a good idea, becuase it requires specific steps to set up, and the drivers, if not updated, do not support the card. You may come upon ancient motherboards with neither AGP or PCI, but please don't waste your time trying to reuse them.

Due to the evolution of new graphics cards on the serial PCI-Express Technology, current newer motherboards have the following connections:

PCI-Express 16x for mainstream graphics cards (4 times speed of AGP 8x)
PCI-Express 1x for faster expansion cards (replacing older PCI)
PCI for use of old expansion cards (would be phased out)
Older AGP 8x graphics cards are generally being phased out for PCI-Express 16x, as the speed and efficiency is about 4 times that of the AGP 8x technology. Old PCI cards are either now built into the motherboard (for sound cards, LAN cards, IEEE 1394 firewire and USB 2.0 interfaces) or becoming PCI-Express variants.

Other Connectors
Some considerations for other connectors and expansions include

USB - the number and version of USB connectors (USB 1.0, 1.1 or 2.0)
On-Board Sound Card - Stereo, 3.1, 5.1, 6.1, 7.1, 8.1
On-Board Graphics Card (Phasing Out)
On-Board Base 100 LAN Card
Serial COM or Parallel Printer Ports
On-Board IEEE 1394 Firewire
At least 6 USB 2.0 ports are recommended for high speed access. On-Board Graphics cards are generally becoming obsolete as they cannot match the newer PCI-Express 16x technology, especially for gaming where high cooling and efficiency is required. USB ports sometimes can come bundled into the front of your computer case for easier access. (Most on-board graphics chipsets are Intel's Extreme Graphics (2), a very obsolete graphics interface.)

Modern motherboards usually come with onboard sound, which is more than enough for the average user. If you are particular about audio quality or plan to use your computer to record high-end audio, you may prefer to use a dedicated sound card (preferably PCI-Express 1x). Some high-end motherboards support on-board 5.1 Channel Dolby surround sounds so this may also be a consideration.

Onboard graphics are very acceptable for anyone not playing performance demanding 3D games or using 3D graphics applications such as Computer Aided Drafting (CAD). Onboard graphics will use a small amount of system RAM as graphics memory (often called shared memory). Purchasing a motherboard with a built-in graphics card is an easy way to save money for an office computer.

If you want gigabit Ethernet capabilities, you should purchase a motherboard with the feature built in. By being built into the motherboard, it will have a faster link to all your components than it would through a PCI expansion card. Also, if you'd like to import Digital Video (DV) onto your system, many higher-end motherboards offer onboard FireWire ports.

If you are upgrading an older computer, keep in mind the motherboard's number and type of expansion board slots.

RAM (random access memory)
The amount of RAM you use is dependent on the purpose that you want to use it for. Older versions of Windows and Linux will run comfortably, though slowly at times, on 128 MB. Some newer operating systems such as Windows XP require 256MB of RAM to run. Many people now have 512 MB or more for better performance. Users of modern games and graphics software, or people who may wish to host Internet services such as a Web site, may want 1 GB or more.

Another thing to consider when choosing the amount of RAM for your system is your graphics card. Most motherboard-integrated graphics chips and PCI Express graphics cards marketed with the "Turbo Cache" feature will use system memory to store information related to rendering graphics; this system memory is generally not available at all to the operating system. On average, these graphics processors will use between 64MB and 512MB of system memory for rendering purposes.

The actual type of RAM you will need will depend on the motherboard and chipset you get. Most current motherboards use DDR (Double Data Rate) RAM. The Intel 915/925 chipsets use DDR2 RAM. Chipsets that use dual-channel memory require you to use two identical (in terms of size and speed) sticks of RAM. Your RAM should usually operate at the same clock speed as the CPU's Front Side Bus (FSB). Your motherboard may not be able to run RAM slower than the FSB, and using RAM faster than the FSB will simply have it run at the same speed as your FSB. Buying low-latency RAM will help with overclocking your FSB, which can be of use to people who want to get more speed from their system.

If you are upgrading from an existing computer, it is best to check with a user group to see if your machine requires specific kinds of RAM. Many computer OEMs, such as Gateway and HP, require custom RAM, and generic RAM available from most computer stores may cause compatibility problems in such systems.

RAM have different bandwidths, ie 400, 533, 600, 733, 800, the current trend is moving from DDR2-400 RAM to DDR2-533 RAM as it is more efficient. Higher end models are very expensive unless you find it worth the investment.

Labeling of RAM
RAM are labelled by its Memory Size (In MB) and clockspeed (or bandwidth).

SDRAM (Synchronous Dynamic RAM) is labeled by its clock speed in megahertz (MHz). For example, PC133 RAM runs at 133MHz. SDRAM is nearly obsolete as nearly all motherboards have withdrawn support for SDRAM. It is now superceded by the more efficient DDR RAM.

128MB SD-133 = 128MB PC133 RAM
DDR RAM can be labeled in two different ways. It can be labeled by approximate bandwidth; as an example, 400MHz-effective DDR RAM has approximately 3.2GB/s of bandwidth, so it is commonly labeled as PC3200. It can also be labeled by its effective clock speed; 400MHz effective DDR RAM is also known as DDR-400. There is also DDR and DDR2 labelled as PC and PC2.

256MB DDR-400 = 256MB PC 3200 RAM
256MB DDR2-400 = 256MB PC2 3200 RAM
DDR RAM has two versions DDR (also DDRI) and DDR2 (or DDRII)

DDR supports DDR-200, DDR-266, DDR-333, DDR-400 (mainstream) and DDR-533 (rare)
DDR2 supports DDR-400, DDR-533 (mainstream) and rare/expensive DDR-667, DDR-800, DDR-1066

Hard drive
Things to consider when shopping for a hard drive:

Interface
The interface of a drive is how the hard drive comunicates with the rest of the computer. The following hard driver interfaces are avalible:
IDE cables can be distinguished by their wide 40-pin connector, coloured first-pin wire, and usually white "ribbon" style cables. This technology is rapidly deteriorating, as it cannot keep up with the increasing speed of current hard drives. IDE based hard drives do not exceed 7,200 RPM.
SATA drives reach up to 10,000 RPM. If you want Serial ATA, you will either need to purchase a motherboard that supports it, or purchase a PCI card that will allow you to connect your hard drive. Note that only certain motherboard implementations will allow you to install Windows XP to a Serial ATA hard drive.
SCSI, although more expensive and less user friendly, is usualy worthwile on high performance workstations and servers. Few consumer desktop motherboards built today support SCSI, and for building a new computer, the work needed to implement it may be outweighed by the relative simplicity and performance of IDE and SATA. SCSI hard drives can reach rotational speeds of up to 15,000 RPM, though these are generaly prohibitively expensive.
USB or IEEE1394 can be used for connecting external drives. An external drive enclosure can convert an internal drive to an external drive.
Cache 
The cache of a Hard drive is a faster media than the hard drive itself, which is normally 2MB (in low-end), 8MB (standard), or 16MB (large disks only) large. The existence of a cache increases the speeds of retrieving short bursts of information, and also prefetches data. Most modern hard drives have 8MB cache, improving performance with a relatively small price difference when compared to 2MB.
Formfactor
3.5 inches is usually used in desktops.
2.5 inches is usually used in laptops.
Capacity 
As a rule-of-thumb minimum, you will need a hard drive capable of holding at least 20GB, although the largest drives available on the market can contain 1TB (1000GB). Few people will need disks this large - for most people, somewhere in the range of 80-200GB will be sufficient. The amount of space you will need can depend on many factors, such as how many high-end games and programs you want to install, how many media files you wish to store, or how many high-quality videos you want to render. It is usually better to get a hard drive with a capacity slightly larger than you anticipate using, in case you need more in the future. However, should you run out of space, you may add an additional hard drive if you have any free IDE or Serial ATA connectors, or through an external interface, such as USB or FireWire.
Rotational Speed 
The speed that the hard drives platters spin at. However drives above 7,200 RPM usually have limited capacity, and a much higher price than 7,200RPM drives of the same capacity, making drives above 7,200RPM not ideal for the desktop.
Warranty 
Many manufactures offer warranties ranging from 30 days (typically OEM) up to five years. It is well worth spending an extra few dollars to extend the drive warranty as long as possible.

Secondary components
These components are important to your computer, but are not as central and necessary as the Core Components.

Video output
For a computer to use a display for monitoring it will need some form of video card into which a display can be plugged. The majority of home and office computers, which predominatly use 2D graphics for office applications and web surfing can use an 'onboard' or integrated graphic processor which will be included on most low to mid range mainboards. For building a computer for gaming, or 3D modelling, a good quality graphics card will be needed.

Currently, two companies dominate the 3D graphics accelerator market nVIDIA and ATI. nVIDIA and ATI build their own graphics products, and license their technologies to other companies. Each brand's similar models have comparable performance levels, and each brand has its own supporters. Video cards have their own RAM, and many of the same rules that dominate the motherboard RAM field apply here: the more RAM, and the faster it is, the better the performance will be. Most applications require at least 32MB of video RAM, although 128MB is rapidly becoming the new standard. On the other end, 512MB video cards top the consumer end of the video card market. As a rule of thumb, if you want a high end video card, you need a minimum of 128MB of video memory -- preferably 256MB. Don't be fooled, though; memory is only part of the card and the actual video processor is more important than the memory. It is important to understand that an integrated graphics card uses the system's RAM, and relies heavily on your system's CPU. This will mean slow performance for graphic-intensive software, such as games.

It is generally better to choose your video card based on your own research, as everyone has slightly different needs. Many video card and chip makers are known to measure their products' performances in ways that you may not find practical. A good video card is often much more than a robust 3D renderer; be sure to examine what you want and need your card to do, such as digital (DVI) output, TV output, multiple-monitor support, built-in TV tuners and video input. Another reason you need to carefully research is that manufacturers will often use confusing model numbers designed to make a card sound better than it is to sell it better. For example, the Geforce 4 MX series of cards claim to be a "Geforce 4," however, the actual processor is closer to a Geforce 2, only more powerful, meaning that these cards actually lack many features available even to the Geforce 3 series. However, when these cards were first produced, they were considerably cheaper than a real Geforce 4 (the TI series) making them an ideal choice if you were more interested in working on a spreadsheet than in playing games. For this sort of reason, you have to carefully pick your card depending on your needs. TV outputs can easily be adapted to your computer by using a DVI - Component Video cable.

Newer technologies such as SLI allow the use of two video cards to render the same video scene, similar to using two CPUs or a dual-core CPU. These systems tend to be very expensive, as only the latest video cards offer this option, and you'll need two of them. However, it can be a useful upgrade path to consider. A SLI-capable motherboard is usually not much more expensive than the regular model, and will work fine with a single video card. You can use it with one card now, and buy another one in the future (which will probably be much cheaper by then), which means you will take advantage of your old video card too.

Interface
There are four different graphics card interfaces: integrated, PCI, AGP and PCI-Express.

Most retail computers will ship with an integrated graphics card. This means that if you are looking at playing games you will need to upgrade. Most mainboards that have integrated graphics will also have one of the other three interfaces so it isn't hard to place a new card to suit your needs if the need ever arises.

Old video cards use the standard PCI slots that are now obsolete due to limited speed and memory. PCI cannot transfer data very quickly, so a system with such a card will often seem to "jump" or halt for short periods when data is being transfered. These cards are needed for a few rare systems lacking an AGP slot (usually low end desktop systems designed to be cheap.) They are also useful for adding aditonal video cards to a system.

Most video cards bought in the last 2 years are of the AGP standard. There are 4 different speed and bandwidths of AGP, 1x, 2x, 4x and 8x. While 8x is the fastest and most common for high end products, the true performance of your AGP card is limited by the lower AGP value of your graphics card and motherboard. For example, an AGP 8x card on a 4x motherboard can only run at up to 4x. AGP will be phased out and there will not be an AGP 16x due to technical limitations, and size necessarily.

The newest trend in graphics card is the PCI-Express (not to be confused with PCI-X) system that supports up to 16x speeds. This is new technology and is generally more expensive but it runs at higher speeds. Some newer graphics cards come in both AGP and PCI-E 16x models, such as the Radeon x800 and the GeForce 6800 series. The newest models of graphics cards, such as the GeForce 7800 and the Radeon X1800, are only made for the PCI-E 16x. (Most motherboards have only one PCI-E 16x while having plenty of PCI-E 1x slots... so make sure you use the right one.) Motherboards with 2 PCI-Express 16x slots can combine the power of 2 video cards using technologies known as SLI for NVidia, and CrossFire for ATI. However, you will have to match the video cards to a motherboard supporting the multiple card technology of choice, and use two similar video cards that both support dual video cards.

Keep in mind that to provide best picture quality and to prevent scaling, your graphics card must be capable of displaying same resolution as your LCD display's native resolution.

CD/DVD
Optical drives have progressed a long way in the past few years, and you can now easily purchase DVD writers that are capable of burning 9GB of data to a disk for an insignificant amount of money. Even if you don't plan on watching or copying DVDs on your computer, it is still worth purchasing a burner for their superior backup capabilities.

When purchasing a DVD writer, you will want one that is capable of burning both the '+' and '-' standards, and they should also be Dual Layer compatible. This will ensure that you can burn to almost all recordable DVDs currently on the market (the other major format, DVD-RAM is almost unused, for the most part, so don't worry about it).

Floppy drive
Though generally not needed, floppy drives are often installed anyway. Floppy drives have been made obsolete in recent years by devices such as USB "Thumb Drives" and CD writers. Floppy drives are sometimes required for BIOS updates and exchanging small files with older computers. Floppy drives block air movement with wide cables, and can make computers set to check the drive take longer to start (most have an option in their bios to disable this.) The drives and disks are also notoriously unreliable. One option to overcome the cable problem and to make it easier to install is to buy an external USB floppy drive. These are potentially a little bit faster and can be plugged into a different system (such as a laptop without a floppy drive.) However, not all systems support booting from a USB floppy drive -- most notably older motherboards. Most newer systems do now though. A USB floppy drive is considerably more expensive and since floppy drives are not needed much anymore, this is rarely a useful option. You can easily get a thumb drive holding more than 50 times as much as one floppy disk for the same price as a USB floppy drive.

Sound card
Most motherboards have built-in sound features. These are often adequate for most users. However, you can purchase a good sound card and speakers at relatively low cost - a few dollars at the low end can make an enormous difference in the range and clarity of sound. Also, these onboard systems tend to use more system resources, so you are better off with a real soundcard for gaming.

Good quality in sound cards depends on a few factors. The digital-analog conversion (DAC) is generally the most important stage for general clarity, but it is a poorly measurable process. Reviews, especially those from audiophile sources, are worth consulting for this; but don't go purely by specifications, as many different models with similar specs can produce completely different results. Cards may offer digital (S/PDIF) output, in which case the DAC process is moved from your sound card either to a dedicated receiver or to one built into your speakers.

Sound cards made for gaming or professional music tend to do outstandingly well for their particular purpose. In games various effects are oftentimes applied to the sound in real-time, and a gaming sound card will be able to do this processing on-board, instead of using your CPU for the task. Professional music cards tend to be built both for maximum sound quality and low latency (transmission delay) input and output, and include more and/or different kinds of inputs than those of consumer cards.

Comments
  • Comment #1 (Posted by Pat)
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    I know you couldn't itemize costs, but it would have been good to estimate a cost for each item. Very informative information.
     
  • Comment #2 (Posted by Vince)
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    After reading it twice, i think i have digested about half of all the technical stuffs u explained. I will read again a 3rd time because this article is so throughly to pass by. Thanks to you, i'm no longer a computer dummy. This article is very informative and well explained. I would recommend it to everybody.
     
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