The magazine of the Melbourne PC User Group
Building a PC on the Dining Room Table
Les Bell		  

Les Bell guides his 9-year-old through the complete assembly of a PC — follow this step-by-step exercise and you will learn heaps!

Note:  All photos used in this article may be viewed at a larger size by clicking on the image displayed.

Often I've wondered exactly how difficult it is to build your own PC. To me, it doesn't seem difficult, but I've been doing it for years.
 
So, I set the task as an exercise for my 9-y-o daughter. In the photos that accompany this article, she did all the work while I took the photos - I provided guidance but never touched the computer from go to whoa. I think we can conclude that if a nine-year-old can do it, it can't be that hard.

Can you save money by building your own computer? Not really - it's hard to beat the bang for the buck that you get from Dell and other low-end suppliers these days. What you will get is better control over the components used - you can go for high quality if you want - and you will gain a better understanding of how the thing works. It also makes it much easier for you to replace failed components - such as power supplies or CD-ROM drives - later in the machine's life. That's certainly easier than lugging the entire machine to a dealer's workshop.


Figure 1. The pile of parts on the dining room
table, ready to begin.


Figure 2. The system board usually comes with
 required cables and connectors, a manual and a
CD-ROM of drivers.


Figure 3. The system board itself is supplied in an
anti-static bag and should be kept there until
you're ready to mount it in the case.


Figure 4. Only a few tools are needed. From left to right: pearl catch, Phillips screwdriver, needle-nose pliers, grounding strap.

Step 1. Collect the Components

You will need the following parts, with some variations:

Case

The case includes the power supply (see Figure 6), and comes with a bag of assorted hardware - screws, mounting posts, etc. Choose a case to suit the motherboard - a micro-ATX (style) motherboard can fit in a mini-tower enclosure, while a conventional ATX (style) board will require at least a midi-tower format, and you might choose a full-size tower if you intend to install lots of drives eg. tape drives, RAID arrays and so on.

The System Board
(motherboard, mainboard, whatever you want to call it)

The mainboard contains the various I/O port chips and their connectors. Most boards have parallel and serial ports, connectors for hard drive, CD-ROM and floppy disk drives, etc. as well as connectors for the front panel power switch, power LED, reset switch, and so on. Some mother-boards also have an onboard sound card, Ethernet (for networks) and even graphics (though the latter may be avoided by the games-players especially, as the performance of onboard graphics tends to lag behind the capabilities of separate, dedicated graphics cards, and may also steal part of main memory). The system board will also have empty sockets for the processor and RAM - you will have to decide what type of processor and how much RAM to use. In this article, we've used a VIA P4X400ATX motherboard, but looking around my office I can see systems built around Asus, Aopen, Intel and other brands of motherboard.

Processor, Heatsink and Fan

It's up to you how much you should spend on a processor - I always find that the high-end processors don't offer as much bang for the buck as their slower counterparts. In fact, if you graph price against performance, you'll find there's a knee in the curve and that's where I tend to buy. Just make sure that you buy the right type of processor to match your mother- board - a board designed for an AMD Athlon processor cannot accept an Intel processor, and vice versa.


Figure 5. At the rear of the case is a section where
the system board's ATX connectors will protrude. If the holes here do not match the connectors on the
 motherboard, you can usually pop this out and
replace it with a plate supplied with the motherboard.


Figure 6. The power supply sits at the top rear of
the case.


Figure 7. With the case resting on its side, you
can see the drive bays - 5.25 inch bays at the
top for CD-ROM drives, etc. and 3.5 inch bays at
the bottom where the floppy disk and hard drives
will mount.


Figure 8. At the bottom of the case you can see the various wires for the power switch, reset switch, speaker (red and black) and a ribbon cable which
goes to the front panel USB and audio connectors.

RAM

It's hard to go wrong here - most current motherboards use 184-pin DDR (Double Data Rate) DIMMs (Dual Inline Memory Modules). Check the supplier's information on the mother- board - it will usually say something like "3XDDR400", indicating it has three sockets for 184-pin DDR DIMMs at 400 MHz front side bus speed.

Hard Disk Drive(s)

Most low-end systems use IDE drives, but SATA (Serial ATA) is gradually creeping down the market and offers higher performance. Again, check the spec sheet on the motherboard and make sure that you order the right type of disk drive.

CD-ROM, CD/RW or DVD-ROM drive

Your choice here is limited primarily by budget and intended application.

Video Card
(not needed if you use the motherboard's onboard graphics)

As mentioned above, dedicated gamers will want to splurge on a high-end graphics card - most of which cost more than the motherboard. However, if all you want is an office machine for word processing, e-mail, etc. the onboard graphics of many motherboards is just fine. Make sure when you order your parts that you know whether you'll need a graphics card or not.

Network Card
(but may be on the mainboard)

Again, many motherboards have onboard Ethernet these days.

Sound Card
(but may be on the mainboard)
Sound is very commonly onboard today.

Floppy Disk Drive

Actually, you probably don't need this, these days, but it's easier to pay $10 and install one now, than have to remove the cover and install it later when you discover you do need it.

Keyboard, Mouse, and Monitor

Technically, these are peripherals and not part of the computer, but if you want to use it...


Figure 9. This is where the motherboard will be
 mounted. The brass spacers should line up
with the holes in the motherboard.


Figure 10. Slide the motherboard gently into
position so that the connectors at the rear
mate with the holes in the back of the case.


Figure 11. Once the motherboard is in place, insert screws into the mounting posts and tighten.


Figure 12 If you drop a screw, a pearl catch
helps you retrieve it from inaccessible corners.


Figure 13. The connectors at the rear of
the motherboard align neatly with the holes
in the case.


Figure 14. Open your motherboard manual and find
the diagram that identifies all the connectors.

Step 2 - Clear a Workspace and Get Out Your Tools.

The dining room table is fine - just cover it with some thick cloth or carpet (natural fibres only, to avoid static) so that you won't cause scratches as you move the computer around.

Tools Required
 
Phillips head screwdriver - this is the familiar green-handled "crosspoint" screwdriver. Almost every screw in a PC is a Phillips type, although you may come across some conventional screws for securing hard drives, and some computers - most notably Compaq - use Torx screws, which have a six-sided socket in the head.

Needle-nosed pliers are useful, especially for sliding cable connectors over pins on the motherboard.

An earthing wrist-strap is a good idea for eliminating static discharge damage to sensitive components like memory SIMMs, the processor, etc.

Finally, (see Figure 4) that strange-looking silver gizmo on the left is a pearl catch. When you depress the plunger, three small wires stretch out of the end, forming a claw (see Figure 12) that can be used to retrieve a screw from where it rolled under the back corner of the motherboard.
 
Take care, when handling the processor, memory modules and expansion cards, to avoid static discharges which can damage these devices. For example, when installing DIMMs, I always place the anti-static bag onto the power supply (or another area of bare metal on the computer) and then spread my hands over it, to ensure that the computer, the bag, the DIMM and I are all at the same electrostatic potential. Then I slide the DIMM out and insert it. Static discharges do not necessarily cause instant component failure, but they can cause cracks in the semiconductor surface, cracks that will later propagate and cause premature failure. So, it's always worth taking anti-static precautions, such as ensuring you are not wearing nylon or other artificial fibres that are known to build up static.

Step 3 - Get Started

Unpack the computer case, and remove the cover or side panel to expose the innards. Remove the bag of screws. Now unpack the mother-board from its box, have a good look, and work out how it will be oriented inside the case. Note the spacers that will support the motherboard - they will have to line up with the screw holes in the board (see Figure 9). Remove the motherboard from its anti-static bag and slide it into place. With an ATX style mother-board, the rear connectors will have to match up with the cut-outs in the back of the case - if they do not, you will probably find that the case panel can be popped out and replaced with one that came with the motherboard.

There might be six or seven screws for the motherboard. In our case, it was six. When inserting the motherboard, be careful not to bend it. Flexing the motherboard can create hairline cracks in the printed circuit board traces, and this can produce intermittent faults that can be extremely time-consuming (read: expensive) to track down and fix.

Do up the screws loosely at first, and then go around a second time, tightening them. Once the motherboard is in place, you can attach the front panel connectors, with careful reference to the motherboard's manual.

The front panel connectors are:

  • speaker - often a 3-pin-wide connector, with only the outer two pins connected. Polarity (which way round it goes) is not really important.
  • power LED
  • ATX power switch
  • Sleep LED (sometimes)
  • HDD LED
  • Reset switch

Your motherboard/case combination may also support additional connectors, such as USB and front panel audio. The trick here is to take your time and carefully match up the connectors with the corresponding pins on the motherboard. Sometimes it can be difficult to figure out which way round things go, but by rotating the manual to match the mother- board, you can usually sort it out, and it's difficult to damage anything by inserting it backwards.

You will also need to attach the power leads to the motherboard. This is done through a large nylon block connector which can only go in one place - it's hard to get this one wrong. Pentium IV processors require a second (ATX 12V connector) which has only four pins.


Figure 15. Each of the front-panel leads must be attached to the corresponding pins or connector
on the motherboard. In the foreground you can see the reset switch (blue/white) and hard disk drive activity LED (red/white), while to the rear are the speaker (red/black) and the power switch (???)
(green/white).


Figure 16. Another view of the front panel
switch/LED connectors


Figure 17. Before inserting the processor and
memory, it's a good idea to attach a grounding
strap to the bare metal of the case.


Figure 18. The processor is supplied in a sealed
plastic case with the matching heatsink/fan combination (top)


Figure 19. The processor will be inserted into a
Zero Insertion Force (ZIF) socket. Before it can
be inserted, you must raise the lever at the side
of the socket.


Figure 20. The processor can now be dropped into
the socket, taking care to align the marked corner
of its package (closest to the camera) with the
marked corner of the ZIF socket. No force will be required - if the processor does not just drop into place then it is misaligned and you should check
its orientation. Once it's dropped in, move the
lever back down until it is parallel to the board -
the processor will be securely clipped into place.


Figure 21. The heat sink and fan can now be
clipped over the processor. Note: Heat sinks and
fans vary in their design and construction. Your
model may be slightly different.

Step 4 - The Processor

The processor itself is easy to insert, as it goes into a Zero Insertion Force (ZIF) socket. A small lever opens the connector, and the processor will literally drop into place, provided that it's aligned correctly. Usually there is a mark on one corner which matches one corner of the socket, but you can also examine the pattern of pins on the underside of the processor to figure it out.

The processor generates so much heat that it needs a heatsink and fan combination, and it must make good contact with the heatsink. The bottom of the heatsink usually has a layer of a thermally-conductive paste applied, to help it mate with the metal top of the processor package. Don't scratch or scrape at this paste - it's meant to be there.

The heatsink will loosely clip onto the processor socket and can then be tightened by folding over a couple of levers on the top. Once that's been done you attach the fan power connector to the motherboard - usually it's keyed so that it won't go in the wrong way.
 


Figure 22. Once the heat sink has engaged with
the clips beside the processor, you can clamp it
down by flipping the levers at either side of the heatsink.


Figure 23. Clamping down the heat sink and fan. Notice the three DIMM sockets in the foreground, where the memory will be inserted.


Figure 24. Now the fan power cable can be
attached to the motherboard's CPU fan
power connector.


Figure 25. Next, attach the power supply leads
to the motherboard.


Figure 26. Pentium IV and Celeron motherboards
will also require an additional power supply
connector (the ATX 12V connector).


Figure 27. When removing a DIMM, prior to
insertion, make sure that your hands, the bag,
the DIMM and the computer are all at the same potential by placing the bag on the bare metal
of the case.
Step 5 - Memory

Most new motherboards today have three or four sockets for 184-pin DIMM memory modules; they're easy to spot as they're in a row, usually close to the processor, and they have ears that are used to secure the DIMMs in place. DIMMs are supplied in anti-static bags and should not be handled unnecessarily. Gently slide the memory out of its bag, match up the keys in the edge connector with the teeth in the socket and push the DIMM gently but firmly down into its socket. As you are pushing it home, the ears at each end will automatically rise, clamping the module into place.

Step 6 - The Drives

Generally you will want at least one hard drive, a CD-ROM or DVD-ROM drive and a floppy disk drive in your machine. To secure these in place, you will need access to both sides of the drive bays, so you may have to remove the right side cover of the computer (see Figure 32 below).

Before inserting the hard drive or CD/DVD drive, make sure that it is configured correctly. For best performance, you should have two IDE ribbon cables - one for the primary IDE controller and one for the secondary - and you should configure the hard drive so that it is the master device on the primary controller, while the CD/DVD is master device on the secondary IDE controller. Other configurations are possible, such as having both devices on the same IDE cable/controller - but remember that both devices will run at the speed of the slower, usually slowing down the hard drive to the speed of the CD/DVD.
 


Figure 28. If you've only removed one side of your computer case cover, you'll now need to remove
the right side so that you can get access to the
screw holes on that side of the drive bays.


Figure 29. Before inserting the hard drive, make
sure it is configured correctly. If it's the only hard
 drive, it should be configured as master, not slave.
A diagram on the drive will usually indicate whether
a jumper has to be added or one removed (and this
is where those needle-nosed pliers prove useful).


Figure 30. Gently slide the hard drive into a 3.5
inch bay - preferably one that is not behind a
pop-out panel, as those will be needed for
floppy drives, tape drives, etc.


Figure 31. At least two screw-holes on each side
of the drive will align with the slots in the drive
bay. Insert four screws from the bag of hardware
that came with the case, and then tighten them.


In most cases, the drives will already have links (jumpers) in the correct positions, but you may need to move them. Do this before you insert the drives, as seeing the links and especially moving them is usually impossible once they are screwed in place.

The hard drive usually goes in one of the lower bays - probably one that is hidden behind the lower part of the front panel, and it goes in with the large nylon four-pin power connector on the right, as seen from the rear (this usually means with the electronics side down, too). Gently slide it into place and secure it with four screws from your hardware bag. However, both the CD/DVD and floppy drives must project through the front panel, and so you will have to pop out the plastic blanking plates in those positions - and possibly metal plates behind that. In some cases, this will require you to lever the metal blank out of the way and "worry" it until it breaks off. Others have ingenious metal clips that can only be accessed by removing the entire front of the case (there is often a clip behind the base of the front panel to enable this).

Once you have removed these, you can slide the CD/DVD and floppy drives into place and secure them, each with four screws.
 


Figure 32. Access to the right side of the drive
bays may require you to remove the other side
panel of the computer case.


Figure 33. The floppy disk drive can now be
slid into one of the 3.5 inch bays.


Figure 34. The CD-ROM drive slides into one of the 5.25 inch bays, usually at the top of the computer.


Figure 35. As with the hard disk drive, make sure its jumper is set correctly (usually for master) before
you put it in, as it will be difficult to see, let alone change, once it's in place. Here you can see, from
left to right, the digital and analogue audio
connectors, configuration jumper (links), data connector and power connector.


Figure 36. If you need to move a jumper - for
example, to change the drive from slave to
master - then extract it gently with needle-nosed pliers and reinsert it in the correct position.


Figure 37. The audio cable from the CD-ROM drive usually attaches to the motherboard somewhere
near the rear panel audio connectors.

Step 7 - Cabling

Now you can cable the various drives to the motherboard and power supply. Start with the CD/DVD audio cable - this goes from the audio connector at the left side of the CD/DVD (as seen from the rear) to a matching connector on the motherboard.

Next, the IDE and floppy data cables. These are ribbon cables - usually grey with a red stripe to indicate pin 1 - and they are sometimes keyed so that they cannot be inserted the wrong way round, for example, by having a pin removed from the connector on the drive and a corresponding lack of a hole on the cable connector. But sometimes, they are not - particularly at the mother- board end. The good news is that it seems to be impossible to blow up either a drive or motherboard by connecting it the wrong way round - I've done it many times, never with fatal consequences. The motherboard manual - and possibly silk-screening on the board itself - will indicate which is pin 1 of the IDE connector, and you should insert the cable with the red stripe at this end of the connector and similarly, the red stripe adjacent to pin 1 at the drive, which is usually the right hand end as seen from the rear (nearest to the power cable connector).

The cable from the hard drive should go into the primary IDE connector while the CD/DVD goes to the secondary IDE connector. Finally, the floppy cable, which is smaller, goes to the floppy connector on the mother-board.

Don't worry too much about tidying the cables at this stage - you can leave that until after you've tested the system.

Finally, the power cables. There will be various cable tails from the power supply, with red, black and yellow wires and blocky nylon connectors. These go into the power connectors, which are almost always at the right end of the drives, as seen from the rear. Try to organise to feed adjacent drives off the same pair of connectors at the end of one tail, as shown here, with the large connector for the hard drive and the small one for the floppy drive.


Figure 38. Once the drives have been screwed
into place, you can start attaching the data
cables. The narrowest ribbon cable connects the floppy disk drive to the floppy disk controller
(FDC) connector on the motherboard. Here you
can see the motherboard drive cable connectors - furthest away (black with orange ears) is the
floppy disk cable, then the red one in the middle
is the primary IDE connector and the white one
is the secondary IDE connector.


Figure 39. Now the other end of the primary IDE
cable has been plugged into the hard drive.


Figure 40. In the same way, insert the other IDE
cable into the CD-ROM drive.


Figure 41. Once the data cables have been
inserted, the power connectors can be attached. Here, a large nylon power connector has a
pick-off to a smaller connector, allowing both the
hard drive and floppy drive to get power from the
same cable.


Figure 42. In the same way as for DIMMs, you
should ensure that the antistatic bag of any expansion cards is grounded before pulling the
cards out.

Step 8 - Expansion Cards

Now you can install any expansion cards, such as graphics card, network cards or modem.
 
The graphics card goes in an AGP slot, which is the one closest to the processor. Before inserting it, you will need to push out a metal blanking plate at the rear of the computer (see Figure 43 below). Gently push the card into place, and inspect it to make sure it is inserted squarely and mated correctly with the connector. In the case of an AGP connector, you may need to push over and latch the lever at the end of the connector. You can then take one of the screws from your hardware bag and secure the card in place by its mounting bracket.

Network cards, modems and other cards will go in the remaining PCI sockets, with a similar procedure. You may also have additional connectors that augment the motherboard's own connectors - for example, the VIA motherboard shown here has five-channel audio output and so it has additional connectors which mount on a bracket and attach to the motherboard via a fly-lead. The length of this lead may limit where you can put the connector, and you may have to swap cards around to get the correct layout.


Figure 43. Before inserting an expansion card,
you may have to prise out the metal blanking plate
at the back of the case.


Figure 44. When inserting an expansion card,
make sure that it mates with the socket precisely
and correctly. This card being inserted is an AGP
graphics card.


Figure 45. The pearl catch is always handy
when a dropped screw has to be retrieved.


Figure 46. As you tighten these screws watch
carefully that a bent bracket isn't causing the
card's edge connector to become misaligned
with the socket.


Figure 47. With all drives bolted in place, data
and power cables connected, it's time for a final check, then to power up and test the beast.


Figure 48. Once everything checks out, you
should tidy up the cables so as to not impede
air flow through the case.

Step 9 - Check Your Work

I know you can't wait, but it wouldn't hurt to give everything the once-over and just make sure that all connectors are in place, all expansion cards are correctly and squarely seated, the DIMMs are fully inserted, etc. Spotting a problem at this stage can save you detective work later.

Step 10 - The Moment of Truth

Plug in the keyboard, mouse and video monitor, turn on and warm up the monitor then apply power. Check that the CPU fan spins up immediately, there is air flow from the power supply fan, and the hard drive spins up.

Watch the power-on self test (POST):
  • Does the video card get detected?
  • Does the full amount of memory get detected?
  • Does the hard drive get detected correctly?
  • Does the floppy disk drive get detected correctly?
  • Press the Del key to enter the BIOS setup routines. Check that the date and time are correct, and check that the hard drive has been correctly identified - although it's rare for this to be wrong with modern motherboard and drive combinations. Check the boot device sequence - since you are presumably about to install an operating system by booting from CD, you'll want this to be CD-ROM first, then floppy and then hard drive. You can reset it later.
Step 10a - Problem Determination

If a drive is not recognised, switch off the power and reverse the cable to the drive (assuming it wasn't keyed and therefore could have been in the wrong way to begin with), then power up and try again.

If memory is not being recognised, check your motherboard manual for any rules about the order in which the memory sockets must be used. Modern boards are not strict on this, but older ones often required DIMM sockets to be filled in a particular order. Also, check that the DIMM is seated correctly, both by visual inspection and by extracting and re-seating it.

Check that the drive activity LED flashes when the drive is accessed, rather than staying on. If it's behaving wrongly, reverse its connection.

If all checks out OK, you can go ahead and install an operating system (OS). We chose Red Hat Linux 9, which runs really well on this system, then later we installed Windows XP which gave few problems.

Once you have installed an OS, you should finish up by testing that the floppy drive works OK, checking the network connection, audio output, etc. If all is OK, then power off, and tidy up. Don't run the computer for too long with the cover off - it actually runs cooler with proper air flow through the case.


Figure 49. Replace the side panels and screw
them into place.


Figure 50. A proud young lady savours the
moment.

If reversing the cables or re-inserting connectors or DIMMs doesn't fix a problem, then you might want to try swapping components with another computer. If you swap a memory DIMM into another computer, and now it doesn't work, then it's probably the DIMM that's faulty. The general rule is that, if the fault moves with the component, then the component is faulty - if the fault stays with the original computer, then it must be something else.

Step 11 - Tidy Up

Tidy up the cables inside the case - in some cases, you can fold up long ribbon cables and slip an elastic band around them so they don't get in the way. Make sure that stray wires are clear of fans and connectors, and that any unused wires, such as those for unused buttons and LEDs on the front panel, are folded up and secured in a corner. Once that's done, you can re-attach the cover, and move the computer into its intended position.

Put all the spare parts, driver CDs, and manuals for the motherboard and other components back into the box the motherboard came in, write the computer's name on it, and store it for future use. Then you'll know exactly where to turn if you have to reinstall Windows or perform upgrades later on.

That's it! You now have a new computer.

About the Author
Les Bell is a Sydney-based consultant, author and lecturer who designed his first computer in 1976. He now sits, surrounded by six Linux servers and several desktops which he built himself, while his daughter checks her e-mail on her own computer. You can read more of his articles at http://www.lesbell.com.au. Les is a Red Hat Certified Engineer and a Certified Information Systems Security Professional.

Reprinted from the May 2004 issue of PC Update, the magazine of Melbourne PC User Group, Australia

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