DIY PC - The Specs

Specifying your computer's components.

The actual specifications listed here will all too soon be out of date, however I hope that you will still be able to use this page as a starting point when designing your own system.

Finding a supplier.

  With a little knowledge of the computer press you will be able to select the quality suppliers from the rubbish. It is possible to find a supplier of quality kit which which also manages to keep prices down. While I could list some of these suppliers here in the UK, the market changes making such evaluations go out of date very quickly.

  Some of the larger suppliers take out large multipage ads in which they attempt to teach the reader about the kit that they are in the business of selling. While this can be very useful, don't rely on their word alone. Many adverts are designed to positively mislead the customer. Eg. I personally considered 'matched memory' to be a very misleading concept.

  Although it may look tempting, try not to order from too many different suppliers. Firstly the delivery charges on multiple orders can quickly mount up, and secondly you can find yourself in the frustrating position of waiting for a single, yet crucial part to be delivered. This could be a major part, such as a processor or motherboard, but it could just as well be something simple like a processor fan. In this way one supplier can waste a great deal of your time, when the rest have all delivered promptly. Sadly, late delivery is now increasingly common, since the practice of selling stock multiple times to multiple users has grown more widespread: Businesses know that the first one to lie and say that a particular item is in stock will be the one who gets the order.

  Since you are still looking to keep some sort of guarantee, it would be wise to follow the standard practice for buying a complete PC system: before you place the order on the sales line, give the tech support/returns line a quick try to see how long it takes to get through to. When you do finally get through to a 'techie' you could take the chance to ask them how the goods will be delivered to you: Stripped, bare, instruction-less components can cause problems if you do not have experience of building your own computer. If you do choose suppliers at the cost-cutting end of the market you can be sure that this is another way that they will be saving money.

  The adverts you read do give some details about the goods that you are looking for, however, comparing prices is useless without knowing the full specifications of a piece of hardware. This information can sometimes be prised out of the suppliers, but not often. More often than not the sales team will be working from a terminal, with no idea as to the full details of any of the equipment. You can ask them to go and look at the box for you, but they'll more often than not they'll "get back to you" [The NOT at the start of this phrase is silent]. The best way to choose the actual kit you are going to buy, is to narrow the search down to 3 or 4 possibles using the information in the ads, and then use the makers web sites to make your final decision.

  Software.

  I think it will do no harm at this point to remind you just why you want a PC in the first place... it is to run software. This should be included in your budget now. You should really be specifying your computer, for the software that you want to run. For games playing this probably means a P3, and for Word processing an 8086! (Tee Hee!) Seriously, unless you are in the process of building a 'dream machine', then you should sit yourself down and honestly look at buying the hardware to meet your software requirements.

  The reason for including the software in your budget from the start is simple. If you don't pay out for some decent software, your PC will do almost nothing when you turn it on.

  You will also need to budget for the operating system. Since you are building your own computer, you're not going to get a 'free' copy of Windows 98 like you would had you bought a computer.

  Parts.

You can, if you wish make savings here, by utilising parts from your old computer. For example CD ROM drives, modems or soundcards can be brought back in to do a few more months, or even years of service, while your bank balance recovers. At a pinch older hard disks could be used as backups in the new system, but they should not be used as the main drive, Windows requires that your HD be constantly shuffling data and so an old drive will certainly slow down your new computer to a crawl. However, more importantly, HD are just not built to last long enough for this kind of extended use, so it is better to be safe than sorry. It would also be inappropriate to use an old VGA card since the speed of the video memory can have a vast effect on the overall system performance.

While stripping out certain parts from your old computer is certainly a good idea, it is best to leave the old computer with some degree of functionality left in it: (Video/HD/Floppy disk). For example this web page could just have easily been done on my old system, so old certainly does not mean defunct. This will become more apparent should your new computer ever let you down in the future.

  CPU

  Go for the best processor can afford - without compromising the rest of the system. Here my advice has changed with experience. If you find that your budget is heavily weighted towards the processor take a moment to think: Would the the money you could save by buying a slower chip buy a faster hard disk, or 100MHz motherboard/SDRAM or 3D graphics card? Any of these things might make more of a difference to the overall speed of your system, depending on how you use the machine. Also, by getting a super fast processor are you reducing your software budget? If you are, then you will be sacrificing functionality for speed, which might not be a good idea either, again depending on how you plan to use the machine.

  Whatever chip you decide to buy, try to leave some room for improvement later on. Eg: is there a Slot 1 Pentium which you could replace your new processor for when, in a few months time the prices fall?

  If you are trying to 'wing it' you might want to attempt to over-clock your chip, but I can't recommend it. [See here The previous link is external to this site.

The previous link is external to this site.

for more details on this fun, yet possibly very expensive hobby].

Motherboard.

Currenly the motherboard you choose should have an Intel BX based chipset supporting SDRAM at 100MHz. Whether you decide to go for Socket 7 or Slot 1 etc depends entirely on which processor family you will be using.

  If you are upgrading or using parts from an old system, then you may require plenty of ISA slots. If you are going for SDRAM then try for a board with four banks suitable for SDRAM DIMMs.

  The Motherboard/BIOS should support 2 EIDE devices, have 1 AGP slot and support processors exceeding the one you actually intend to buy. Built in sound/SCSI support would be a worthwhile bonus.

  Once you have narrowed the choice down to a couple of different motherboards, check out the layout of each. Think about the problems you might have working with it, are the DIMM sockets placed too close to the IDE connectors like on my motherboard for example?

Memory

Memory must be the fastest available. Currently the best you can get are SDRAM DIMMs which run with BX chipset motherboards. The memory is set to run at the speed of the motherboard bus which should be 100Hz. Syncronous-DRAM gives about a 10-15% increase in overall system speed over the older EDO memory and helps to prevent the speed of your processor being eaten up by wait states caused by slow memory access.

32Mb is now an absolute minimum requirement, with 64 or even 128Mb being more realistic. You can find some discount memory, but discount memory with some kind of extended guarantee is the real prize, so read the small print.

Graphics Cards.

If you have the money then look out for video cards with dual ported memory, (that would make my life as a graphics programmer much easier!) The graphics bus is a real bottle neck in the PC architecture, with memory refresh, the monitor feed, and the CPU all fighting for control. The CPU has to loose in this battle, since the others must be active for the most part. Make sure your graphics card and motherboard use the new AGP slot (rather than a PCI) to help reduce this problem.

Other considerations are max resolution, Vertical Display Frequencey and 3D acceleration. Max resolution refers not just to the width*height of the pixels on the screen, but also to the bit depth. This latter value decides how many colours you can view onscreen at once. Currently the minumum acceptable would be 1024*768*2 (Hi-colour), requiring 2Mb of display memory. The vertical retrace supported by the graphics card should be above 80Hz by now, since many people can still see the flicker and anything lower will surely give you a headache over time.

Currently hardware 3D acceleration is only really required by games where it goes a long way to relieve the burden from the processor and improves the overall quality of the image no end. The requirement for hardware 3D acceleration will become more widespread for other tasks in the future, but for now it really is just for games players.

Hard Disk.

You should not worry too much about seek times and look for data transfer rates... if you can find them published. EIDE is a acceptable choice over SCSI and is now perfectly capable of supplying the consistent data transfer rates required when mastering CD ROMs. If you are unsure, choose a drive like a good wine... on price! :) Narrow it down to a few contenders and then look up the tech. specs on the makers internet sites.

I personaly prefer to have two hard disks in a system. While backing up is a necessity, it does not hurt to make it as easy as possible, and a second hard disk is probably the easiest way of doing this.

  Monitor.

  Never buy a monitor on the basis of a screen resolution which is specified as 'interlaced'. Interlacing is just about acceptable for the domestic tv, however for the close work required with computing it is entirely inappropriate and always has been.

  If you can, try to go for a 17" monitor. The second best purchase I ever made, this has revolutionised both my work and leisure usage of my PC. If you cannot afford, (or physically support) a 17" monitor, do not buy a so called 14" monitor. Current 15" monitors are infact only 14" across and anything smaller is unacceptable for general usage... do not save money on a cheap monitor!

  As mentioned above, do not go for monitor which cannot support at least a 85Hz refresh rate.

Case.

You will have to buy a case which you know will fit your motherboard. At the time of writing ATX is currently the standard form factor for motherboards. It is important to note that this issue is not just a matter of what motherboard will physically fit into the case, since ATX motherboards also require a very different power connector.

ATX cases are generally far better designed than their AT predecessors. (Many AT cases don't even allow access to all the motherboard sockets eg PS/2 mouse). More thought has gone in to both the cooling and the positioning of the internal components in ATX cases. Combining this with the advanced power management features of ATX, it currently makes ATX the motherboard to go for, even if this does mean throwing away some memory that you might have wanted to keep.

  A properly designed case can help you with your building a great deal. Modern cases allow easy removal of both motherboard and cards, which saves a lot of time.

  The case should come with at least a 230Watt PSU and preferably a 300Watt one, at least then you'd know it was never having to stretch itself.

  Now is also the time to start thinking about heat. Looking inside todays PC one thing is clear, things are getting a great deal hotter. It is not just the processor which is getting hot. The BX chipset has to have its own heatsink and the same goes for the processor on the video card. Things are going to get hot and you are going to need to plan now to make sure they do not burn themselves out prematurely.

  The most important thing you can do for your computer is to provide it with a big enough case. While my baby AT case looked cute and took up no room at all, it did cause the motherboard inside it to warp at its one unsupported edge. The next most important thing is of course cooling. Ideally The fan inside your PSU should contribute to the overall cooling of the whole case. My ATX box, like one of my 486s, has the fan directly over the Pentium which is a good idea. The baby AT case put the fan in its own separate compartment at the top of the machine, making it contribute almost nothing to the overall heat dissipation.

Modern day motherboards include temperature sensors which report back via software the current status of the processor and case. These utilities can be invaluable during the first few weeks of using a machine to check that there is adequate cooling before disaster strikes.

  Modem.

The only advice I would give is not to buy a software modem, see why here.

  Conclusion.

  Work out what you can really afford now. Remember, that although you've got no pushy sales people trying to tempt you with better specs than you actually need, you still might be guilty of over specifying! - If you are equipping an office and you know that a certain workstation will only ever get used for Word processing, then for heavens sake - save some money, and electricity!

Example Specification.

(A little out of date now, but you get the general idea:)

Processor:	PII 400MHz
Motherboard:	100 Mhz BX Motherboard (including 2*USB ports).
Memory:	64Mb SDRAM
Hard drives:	Two, 4.3 Gigabyte hard disks on EIDE/UDMA
Monitor:	17" monitor. (At least: 85Hz at 800*600)
Video card:	AGP Video Card 2D/3D
Sound card:	Sound blaster AWE 32 GOLD
CD-ROM	CD-R 12X read 4X record.
Modem:	56K (V.90 modem) Not HSP or Win-modem!
Disk drive:	Floppy drive
Box:	Case/PSU.
Peripherals:	Wheel-Mouse/Keyboard/Speakers.
Operating System:	MS Windows '98
Applications:	MS Office 2000
	Paint Shop Pro.

A page from James David Chapman's website. Located at: http://www.users.globalnet.co.uk/~jchap/ Site mirrored here at: http://www.j.chap.btinternet.co.uk
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