I thought that one of my responses to a question about building a computer would make a good article, so I'm bringing it in here to clean it up and maybe even find a few pictures to add in.

I'm going to edit this one in place and comment on changes in my replies, it's too long to repeatedly post the article otherwise. Harsh opinions appreciated, particularly if you've built a PC before; point out if I missed anything.

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First, get the appropriate tools. You'll need a Phillips-head screw driver at the bare minimum, and needle-nose pliers can come in handy occasionally. Have a flashlight handy for reading the motherboard when its in the case. If you're smart, also pick up a grounding bracelet, it'll look like a cloth bracelet with a connector on it, to which attaches a cable with an alligator clip which gets connected to something metal and grounded. Wear this at all times while handling any electronics, or you run the very real risk of shorting out your newly purchased toys!

Second, obtain the parts. Here's the minimums you'll need:
  • Computer Case
  • Motherboard
  • Processor
  • Heatsink/Fan Assembly
  • Memory
  • Video Card
  • Optical Drive (e.g. DVD Burner)
  • Hard Drive(s)
  • Monitor
  • Power Supply


Optionally, you can pick a sound card. Although most motherboards nowadays have excellent sound cards, some people truly prefer a dedicated solution. If you have need for one, you can also get a floppy drive. The topic of how to purchase these parts goes beyond the scope of this discussion, so for now I'm going to refer to this generically.

1) Open up your computer case and remove the sides to it. Often the bag of screws is inside the case, move this to the side. You will see a bundle of wires with connectors leading to the front of the case, carefully move these out of the way of the main area of the case. Go to the 5.25" bays in the front of the case and pop one open for your optical drive. (You may have to remove a metal plate if the case has them in the bay. Be careful when doing so, they tend to be sharp so use needle-nose pliers.)

2) Unpack the motherboard from its box, remove it from its static bag and place it on the bag to the side. Move any pack-ins like cables and CDs out of the way, you won't need the cables until later.

3) Open up the bag of screws and pull out the posts. These are screws that tend to be brass colored, are short and accept another screw on top of them. They are used to securely attach the motherboard to the computer case. Inside the case on the back plate where the motherboard is attached, you will see a number of screw holes. Different sets of holes are used for different sizes of motherboards. Take your motherboard and carefully hold it up over the holes to identify which ones are appropriate for your motherboard. Take your posts and screw them in tightly to these holes. If you have more holes than posts, which shouldn't happen with a good case but it could happen, start with the four corners, then move to the middle. It's especially important to have the posts under where cables are connected, to prevent the board from flexing while connecting them.

4) Unpack the hard drive(s) and optical drive (and floppy drive if you have one), and using their provided screws, install them into the case. (It's easier to do this when the motherboard's not in the way, in my experience, but the order isn't terribly important.)

5) Open up your processor and connect it to the motherboard. Use the instructions provided by the motherboard's manual to do this.

6) Open up the heatsink/fan assembly, and attach it carefully to the processor and motherboard. This will attach tightly, so be careful when you do this, as you could damage the motherboard, processor or both if you're careless. Follow the instructions included with the assembly to the letter!
6b) For improved performance, you may consider purchasing a small tube of thermal compound, which tends to transfer heat much more efficiently than the thermal tape that comes standard on most heatsink/fan assemblies. If you choose to do this, then before installing the assembly, remove the thermal tape completely from the assembly, then spread the compound THINLY on the processor itself. Make sure to get full but even coverage.

7) Open up your memory and install it to the motherboard. In order to take advantage of the dual channel properties of most modern motherboards, be sure to follow the diagram in the motherboard's manual. It will tell you what slots to install the memory in to get dual channel performance.

8 ) Now, take the motherboard and place it onto the posts in the case. Once you've lined them up, use screws to secure the motherboard to the posts. Do not overtighten these, these should be just about finger-tight.

9) Take out your power supply, and secure it to the large opening in the back of the computer case using the four screws provided with the power supply. Most cases have this towards the top of the case, but some cases have it on the bottom. If the power supply is not modular, and has all of its cables permanently attached, move these out of the way of the motherboard. We will be attaching these later, as they get in the way very easily.

10) Using the diagram provided in the motherboard's manual, connect the case's bundled wires to the motherboard. You may or may not use all of the wires for this, and you may not use all of the connectors on the motherboard. Every situation is different, but you will always have the following: power switch, power LED, HDD (Hard Disk Drive) LED, reset switch. You may also have a speaker connector as well.

11) Install the video card into its socket carefully. Many PCI-Express sockets have a latch that helps securely hold the card in its slot, so if this is present ensure that the latch is fully engaged before using one of the case screws to attach the video card to the back of the case.

12) If you have any other expansion cards (such as a sound card), or wish to install any extra port headers included with your case (such as extra USB or firewire ports), do so now. Try to leave space between each of the expansion cards to allow for air flow. Connect any headers you install to their respective ports on the motherboard. (Check the motherboard manual for their location.)

13) Grab your Serial-ATA and IDE cables, as necessary, and connect them to the optical drive and hard drive(s). Use the first SATA port available for the master hard drive (may be labeled SATA0 or SATA1). 13b) If you are using IDE devices, a few special rules apply: any IDE device will have a Master/Slave jumper on the back. The first device on the cable (furthest from the motherboard) is the Master, and the second device is the slave. Make sure that the jumper on the device is set appropriately. Always put an optical drive in the slave position if there is both an optical drive and a hard drive, otherwise it is okay to make it the master.
13c) There may also be an optical cable, which has a thin black 4-by-1 connector, about 3/4" wide and 1/4" thick. If you have one, connect this to the optical drive on one end and the motherboard (or sound card) on the other end.

14) Connect the power cables to each of the required connections:
  • There will be a 20 or 24 pin connector for the motherboard.
  • There may be a 4-pin (in a 2x2 design) or 8-pin connector on the motherboard near the processor slot, too.
  • Most modern video cards require one or two 6-pin connectors.
  • IDE devices have a wide 4-pin (4x1 design) connector.
  • SATA devices have a special black power connector that's about 1" wide and 1/4" thick, and the plug is very subtly L-shaped.
  • Floppy drives, as well as some specialized devices, have a small white U-shaped connector (officially named a floppy power cable) that's about 3/4" wide and 1/3"-1/2" tall.


15) Double check every single connector, expansion card and stick of memory to ensure everything is securely connected PRIOR to plugging the power cable into the power supply.

At this point, attach your monitor, keyboard and mouse, plug in the power to the power supply, then try booting up. If you see the BIOS screen, you've successfully built a PC!

See? It's a lot of steps, but it's not that hard at all. You'll probably spend an hour or two doing your first PC.