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Building Your Own PC

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Building your own PC can be both fun and rewarding, and also quite often you'll find it cheaper than buying a pre-built system from a store. One downside however, is that you don't get the technical support or warranties you would get if you purchased a pre-built system from a store.

There are a few things to consider before embarking on a project to build your own computer: your budget, its performance and what you want to use it for. Also, it would help of you knew a bit about computers before reading this entry. For instance there's no point in building a high-performance PC if all you do is browse the web and use basic programs for tasks such as word-processing. Equally if you require a high-performance PC, be realistic with your budget. Once you've worked out what specification/budget you are working to you will need to make sure you have some basic tools, but don't worry as these are fairly inexpensive. Here's a list of the tools that you would need:

  • Precision screwdriver set
  • Miniature long-nosed pliers
  • Miniature side cutters
  • Phillips/Pozi #2 driver
  • Modelling/hobby knife
  • Anti-static wristband

Once you have your tools, have decided on the type of system you are going for and have sorted out your budget, you can start taking into consideration the finer points of the system you are about to build, such as type of CPU, type of memory, etc.


The CPU (Central Processing Unit) (which is sometimes just called a processor), is the part of your computer that carries out most of the work. There are two speeds to consider with the CPU - first of all there is the clock speed, measured in Hz, which tells you how many times the CPU completes a cycle in a second. At the time of writing, processors are up to 3Ghz. The second speed is called the 'bus speed' and is also measured in Hz. Bus speed determines how fast the processor can pass information between itself and other parts of the computer. The third thing to consider with the CPU is the cache size, or the processor's internal 'memory', which is measured in Bytes. There are two main contending manufacturers of CPU, the well known Intel and AMD.


At the time of writing there are two main processors available from Intel - there is the Pentium 4 range of processor and the Celeron. The Pentium 4 is superior to the Celeron in that, a Pentium 4 of equal clock speed to a Celeron will have a faster bus and a larger cache. Also Celerons aren't available in the higher speeds that Pentium 4s are.


As with Intel AMD has two main types of processor, there's the Athlon XP range and the Duron. The fastest Duron is 1.3 GHz and the slowest XP processor is 1.47 GHz so as you can see the Duron is AMD's budget processor.

Intel has the lead over AMD in the raw speed department - at the time of writing the fastest Pentium 4 is 3.07 GHz while the fastest AMD processor is 2.17 GHz, but although Intel has the edge on speed an AMD processor can handle more instructions per cycle. So, comparatively speaking, Hz for Hz, the AMD processor is more powerful than the Intel.


A very important thing to consider with modern processors is thermal protection. If left to, a processor will get extremely hot and burn itself out. Always buy an adequate heat sink and fan for your processor. If you are unsure, both Intel and AMD sell their processors complete with a suitable heat sink and fan.


If the CPU is the 'brain' of the computer, then the motherboard is the 'body'. A small, rather rectangular board, this is what everything connects to and synchronises with. What type of CPU you go for will determine what type of motherboard you can have. If you have chosen an Intel processor you will need a 'Socket' motherboard, and if you have gone with AMD you'll need to go for a 'Socket A' motherboard. Also, some motherboards will not take the fastest processors in a range, so make sure your motherboard is capable of taking the processor you have chosen. Apart from these restrictions you are pretty much free to choose whatever motherboard you wish. So what should you look for in a motherboard?

PCI Slots

PCI (Peripheral Component Interconnect) slots are basically expansion ports for your computer. You can connect all sorts of devices to a PCI slot, from USB ports, modems, soundcards and network cards to DVD decoders and TV-tuners. Think about the peripherals you are going to want in your computer, that do not come onboard (as a part of the motherboard) and this will give you an idea of how many slots you require. Most boards come with five PCI slots and this should be ample.


The AGP (Advanced Graphics Port) is the slot that takes your graphics card. The only thing to consider about the AGP slot is its speed, at the time of writing these are available in 2X, 4X and 8X. Unless you are using your computer for very advanced graphical use, you aren't really going to notice a difference in speed.

Memory Slots

These are the slots that take your computer memory or RAM. There are two types of RAM available, SDRAM and DDR RAM. The former is now being phased out in favour of DDR RAM. The other thing to consider is the maximum amount of memory your motherboard will support. More on RAM later.


Most motherboards now come with USB ports as standard - some have just two and others have more. The other thing to consider is which standard to go for, as there is now USB 2.0, but don't worry as it's backward compatible with regularUSB. The difference between the two lies in the speed of data transfer, but to be honest you won't notice the difference.

IEEE 1394

IEEE 1394, otherwise known as Fire Wire, is a step-up from USB and USB 2.0. Fire Wire is a port, which is used to connect devices such as digital camcorders, although it is being used more and more for other devices. As with USB ports IEEE 1394 can be added to your board later via one of the PCI slots.


LAN (Local Area Network) is also referred to as Ethernet. Some motherboards come with a built-in LAN or Ethernet port, so you don't have to buy a separate network card. You can of course add one later, but you never know when these might come in handy, so if you can, select a motherboard that has Ethernet already built in.


RAID is an acronym for Redundant Array of Inexpensive Discs. Nearly all motherboards come with two IDE channels, with each channel able to take two devices, hard drives, and optical drives (eg CD-Rom) etc. Basically, RAID allows you to add more devices and again RAID can be added later via PCI.


SCSI, pronounced 'Skuzzy,' is the abbreviation for 'Small Computer System Interface'. Not many motherboards come with SCSI built-in, but it is available on a PCI card. It is similar to IDE in the devices it connects to your computer but is basically a lot faster than IDE. Make sure any drives you buy are SCSI drives if you go for this option1.


The majority of motherboards come with some sort of soundcard attached. Some have simple two-channel sound (stereo) while others have six-channel sound (Digital 5.1). Choose one that is suitable for your needs, or buy one separately.


RAM is your workhorse. Adequate RAM means your computer will work at an acceptable speed, won't seem to freeze up as something takes very long and lots of RAM is a very good thing. As mentioned before there are two main types of RAM. First there's the older SDRAM, which is being phased out in favour of DDR RAM. Nowadays, adequate RAM can be anywhere between 128Mb and a Gb or few, depending on your requirements. Usually, RAM is installed in pairs, so two 64MB chips for a total of 128 Mb or two 128 chips for 256Mb2.


There are two speeds of SDRAM, PC100 and PC133, which speed you need depends on the bus speed of your processor. Most likely you will need PC133.


There are currently three speeds of DDR memory - PC2100, PC2700 and PC3000, which are 266 MHz 333 MHz and 400 MHz bus speeds respectively. The type you choose is down to you as they are compatible with modern processors even if their bus speeds are different. However, if your processor has a bus speed of 266 you won't really benefit from having memory with a faster bus speed. The same goes if you have a bus speed of 400 MHz - if your budget allows it you might as well go for 400 MHz memory.

Hard Disk Drives

Size matters! It is pointless buying a 120 GB hard drive if you are going to be saving a few word-processing documents and playing Solitaire. Conversely, if you are likely to be playing modern games and running space-hungry programs for web-developing and such things, you are going to struggle with 20 GB. If you're not sure what size you need 40-60 GB should be a safe bet. The other things you need to consider are speed, measured in rpm (Rotation/Revolution per minute) and cache. There are two speeds 5400rpm and 7200rpm - unless performance is paramount it isn't important which speed you buy. Cache is the hard drive's 'memory' - the larger the cache, the better performing the hard drive.

Optical Drives

These are your CD drives - you can have any combination you like.


CD-ROM is your basic drive; it can read CD-ROMs and music CDs. The only thing to look out for is the read speed, which will look like '48x' or '52x'. What this basically indicates is the speed at which it can read data off the disc.


DVD-ROM is a step up from your CD-ROM as it can also read data DVDs and DVD videos and it doesn't usually cost much more either. One thing you will notice is that the read speed tends to be a bit slower though.


CD-RW is a CD rewriter - this will 'burn' CDs for you so you can store lots of data on one CD, such as for backups; with the correct software you can also make music CDs. It will also read CD-ROMs and music CDs. The speed will be advertised as something like '52x24x52' which is its write speed followed by rewrite speed followed by its read speed. Most CD-RW drives have CD burning software bundled with them.

Combination Drives

You can now also get drives which combine the capabilities of a CD-RW and a DVD-ROM drive. The speed is denoted as follows - '52x24x52x16' - which is the same as for a CD-RW with the DVD read speed tagged on the end.


Then there are DVD-R/DVD-RW drives, that do everything, and this includes 'burning' DVDs! It can read CD-ROM, music CDs, DVD-ROM and DVD movies. It can also 'burn' CDs and DVDs. These, at the time of writing, are fairly expensive costing around £200 (US$310), but it is worth noting there are three types of DVD recorder available. They are; DVD-R/-RW, DVD+R/+RW, and DVD-RAM. So which to go for? DVD-R/-RW was the first format released and is compatible with the majority of standalone DVD players. DVD+R/+RW has some better recording features but is compatible with slightly fewer standalone DVD players. DVD-RAM is rewritable (as are other formats) but supports multi-burns - that is, you can record on it, then later on add another recording without having to redo the previous recording. This makes it more like a removable mini hard drive - however, it is compatible with very few standalone DVD players.

If you already have a home DVD player check which format it is compatible with and buy that format recorder. If you don't have one then choose which ever format you prefer/budget allows and bear this in mind when buying a new DVD player.


The case is the housing for your system; not too much to worry about here as it's mainly about personal aesthetics and budget. There are a couple of things to think about - firstly, make sure you buy a case that will house your motherboard. The most common 'form factor' for motherboards is ATX, and most cases will take different 'form factors' but always double-check.

Secondly, check the amount of bays it has. There are two types of bay - 3.5" and 5.25". The 5.25" bay is what holds your optical drives, also some accessories fit into the 5.25" bays, such as audio front panels. Make sure you have enough bays to house all your drives. 3.5" bays will be both 'exposed' and 'hidden'. The exposed bays house your floppy drive/s. The 'hidden' or internal bays house your hard drive/s. Finally, check that your case comes with a PSU (Power Supply Unit) - some do and some don't. A 300W PSU minimum is recommended for most systems - however, it is probably wise to have at least 350W.

Graphics Card

The first thing to do when selecting a graphics card is to make sure you buy the correct form card for your motherboard. If your motherboard has an AGP slot (most do) then buy an AGP graphics card. If this is not the case, you'll have to make do with a PCI card. Graphics cards have their own memory - the more memory the better the graphics capability of the card - with 32Mb being the minimum that is recommended. If you are likely to play a few games or watch DVDs then 64Mb will be better. 128Mb would be recommended if you play a lot of newer games or really need the capability for photo-editing, etc.

The Rest

The few other things you need don't really warrant a section each so they are summed up here.

Case Fans

It will get very warm inside your system so it's advisable to buy at least a couple of case fans, one for intake and one for 'exhaust', this will keep good airflow in your case. Most cases accept 8cm case fans and these are inexpensive.

Floppy Drive

Amazingly, modern day computers still require a floppy drive, which will only hold 1.44Mb, a tiny amount of data by today's standards. Again, these are inexpensive.


You will more than likely want a modem to connect to the internet. There are two types of standard 56k modem available internal (PCI) and external.

IDE Cable

Almost everything you buy will come complete with everything you need, screws, cables etc. However most motherboards come with only one IDE cable, which means you would only be able to connect two IDE devices.

Keyboard, Mouse and Speakers

It really doesn't matter what you buy here, the only thing to check for is that you have a correctly-fitting mouse and keyboard for your motherboard. It will almost certainly accept PS2 keyboards and mice, but double-check. As for your speakers be sensible - if your motherboard has two-channel (stereo) sound, then it's pointless buying top-of-the-range home cinema speakers. Equally, if your motherboard has six-channel (Digital 5.1) sound it would be wasted on a cheap pair of stereo speakers.

The Build

So now you have all these bits but what on earth do you do with them?

The first thing is to take the time to familiarise yourself with the components - make sure you know what is what, where it goes and how it connects to the motherboard. You should also read through the manual that came with your motherboard and make sure that there are no jumper settings you have to change for your set-up. Make sure you have an adequate and clean working space and that you yourself are clean as well3, mainly your hands. Also, it is always advisable to wear an earth strap whilst handling the parts.

The first thing to do is to mount the motherboard in the case. You will see a lot of holes on the inside wall of your case. These will be marked relating to which are used with which 'form factor' motherboard, so make sure you correctly identify the holes you will be using. Now you will need to screw in some special brass screws called 'elevator screws', which your motherboard then rests on (these are usually supplied with your case). Once the motherboard is correctly seated over these screws you can screw the motherboard into the case.

Once this is done you will need to fit the processor but be very careful when handling the processor as it is very delicate. Follow the instruction manual that came with your motherboard for fitting the processor. Next you will need to attach the heat sink and fan. If, as suggested, you bought a processor complete with heat sink and fan follow the guidelines that come with processor. The power supply for the fan is usually in the form of 3 pins on the motherboard close to the CPU socket, check your manual to locate this.

Next fit your memory modules or RAM. These will only fit one way round in their slots, so do not force them. Once you have them lined up in their slots, gently push down at both ends and the locking clips will come up to lock them in place.

Now fit all of your drives - such as hard disks, floppy disks, CD-ROMs and so on. Be careful when removing the metal panels at the front of the case as the edges tend to be very sharp - the best tools to use are long nosed pliers and side cutters.

Once they are all screwed properly in place, connect the floppy to the motherboard with the floppy cable. This will only fit the motherboard one way round, so make sure the red stripe on the cable is on the left-hand side of the floppy drive as you look at it from the rear.

When connecting the other drives it is advisable to have the hard drive/s on one IDE channel and your optical drives on the other. If only using one hard drive make sure the 'jumpers' on the back are set to master. This will be shown on the top of the hard drive. If you are using two drives, make sure one is set to master and the other to slave. Connect your hard drive/s to the first IDE socket on your motherboard (usually called IDE0); this time make sure the red stripe on the cable is to the right of your hard drives as you look at them from the rear. Now connect your optical drives to the second IDE socket (IDE1). Again make sure one is set to master and the other to slave, as before the red stripe on the cable needs to be to the right of the device as you look at the rear of it.

Finally, with the cable that came with your CD/DVD drive connect the drive to your motherboard/soundcard.

Then you need to fit your graphics card, this will just push in but do not use excessive force. Once this is done add any expansion cards such as a modem or network card to the PCI slots. Again, do not use excessive force.

Now you will need to connect the cables from your case to the motherboard, such as the on/off switch, reset switch, power light and disk activity light. You will need to follow the instruction manual that came with your motherboard to do this.

Now you're almost there - the next step is to attach your case fans to the case. You should have room at the front of the case for at least one which should be your intake fan/s and room at the back for your 'exhaust' fan/s. Once this is done you can connect the PSU to your motherboard, drives and case fans.

Now you need to disable any 'on board' (motherboard) features you don't require, for instance if your motherboard has 'on board' sound or graphics but you have bought your own sound/graphics card, you will need to disable the motherboard's. This is done using 'jumpers', so check your motherboard manual for details on how to do this.

With the system built the final thing to do when you turn your computer on is to make sure your motherboards FSB (bus speed) is matched to your processor's bus speed, so:

  • If you have a 266MHz processor, the motherboard FSB needs to be set to 133MHz,
  • for a 333MHz set it to 166MHz
  • and for 400MHz set it to 200MHz.

This is usually done in the BIOS on start up, however a few motherboards require you to do this via 'jumpers' on the board. Either way you should check your motherboard manual on how to do this.

1Also, SCSI is becoming less common than either USB or Fire Wire, so that might be a better choice.2There are exceptions to this, most notably in Macs, but you're unlikely to want to build one of those yourself - they're much more fun to buy.3This is a simple precaution as you will be handling delicate, expensive electronics and it really would be a shame if you ruined something by accident.

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