How to build a computer

Recently I explained my reasons why you should build your computer. I figure, if I’m going to tell you that you should, then at the very least I ought to tell you how. It’s much easier than you may believe. I think it’s safe to say that the component manufacturers do their best to make it easy – it is in their best interest to sell parts, after all. If you take on a computer-building endeavor, you’ll find that in the end, you’ll have a new, well-built, and cost-effective computer that you can be proud of.

The hardest part of this process is the shopping. There are hundreds of different models with different features for the parts you’re going to need — and they don’t all work together. If you’re not someone who keeps up with all of the technology trends it can quickly feel like you’re drowning in an ocean of PC parts. Luckily some very helpful websites review and offer suggestions on parts. They even produce parts lists tailored to specific computing purposes. I’ve always been a fan of AnandTech and their Buyer’s Guides. AnandTech is a great place to get your feet wet in the sea of computer parts.

Whatever your computer needs may be, the basics of the system remain the same. At the very least, you will need:

  • Computer Case
  • Power Supply
  • Motherboard
  • Memory
  • CPU (and cooling fan)
  • Video
  • Hard drive
  • Input devices (keyboard & mouse are the usual suspects)
  • Monitor
  • Sound
  • Network
  • CD/DVD Burner

In every computer system, there is a “weakest link.” Often, this is the motherboard because builders sink all of their money into a really fast CPU, huge hard drive, and powerful video card, but skimp on the motherboard. I typically find that I have better results with a slightly slower CPU and a higher-quality board. After all, the board in the backbone of the system.

It’s sometimes helpful to think of a computer as a car (it’s sometimes confusing). The chassis is the case, the power supply is the gas, the CPU is the engine, and the cabin and trunk are the hard drive. I’m not sure where the memory fits into this example, but the motherboard is the key – it is what brings everything together. It allows the gas to run to the engine and the engine to turn the drive-shaft, and the drive-shaft to turn the wheels. Sure, you could get a Ferrari engine and put it in the body of a Hyundai, but would you expect the same performance?

Putting it all together

Your parts have arrived, and you’ve got them all lined up, ready to be put into place. Before you begin you’ll also need to assemble your work-space. You’ll need a screwdriver set, a handy reaching tool (for when you inevitably lose a screw in the case), and rubbing alcohol.

Before you unpack anything you need to wash your hands thoroughly. The oil on your hands can cause computer components to overheat and come to an untimely demise. You may also want to use a little rubbing alcohol to really remove the oil from your hands – but I think soap should suffice. It’s important not to touch any of the exposed components or metals on any computer part. Be sure (as much as humanly possible) to hold elements by the side – specifically the motherboard, memory, and CPU. The hard drives and DVD drives are easier to handle.

Start by unpacking and opening up the case. Take the side panel off to expose the inside cabin. Remove any removable hard drive mounting bays or anything else that may get in the way of putting the motherboard in place. Find the parts kit with the screws and risers. Sort out the screws and risers – be sure to put them somewhere so they won’t be knocked to the floor. Determine which screws appropriately fit the motherboard risers.

Inside the case, on the mounting surface, where the motherboard will be mounted, you will see letters (A, B, etc). The ATX form factor is the most common, and probably what you’ll be dealing with. It should be signified with the letter A or ATX. If you’re not sure, check the manual that came with the case. With your fingers, screw in the gold-colored motherboard risers in the appropriate holes.

If you are not sure which mounting holes to use, carefully slide the motherboard into place and see which holes in the case line up with the holes on the motherboard. Be sure to put the risers wherever there is a hole in the motherboard.

In the motherboard box is a panel for the input area of the motherboard. Pop out the panel that came with the case and pop the panel that came with the motherboard in its place.

Mounting the CPU

In the motherboard box, along with a bunch of cables, there may be a foam cushion. Place the motherboard on this cushion to protect the contacts on the underside of the board. If there is no foam cushion place the motherboard on some clean cardboard. Do not work on a hard surface. We will be putting some pressure on the motherboard and a hard surface could damage the underside.

Lift the release for the CPU block (instructions for your specific motherboard should be in your manual.

Unpack the CPU from its box. Again, be careful not to touch any of the pins or the top of the CPU. Align the pins on the CPU with the CPU block on the motherboard. There is only one way a CPU can fit in a motherboard. The CPU should drop right into place. Never force a CPU into place. If it’s not going in, it’s not aligned properly. Lock the CPU into place.

Wipe away any visible fingerprints left where you touched the CPU with a clean cloth that has a little rubbing alcohol on it. Remove the CPU cooling fan from its packaging. Read the directions for mounting the fan in the fan manual and motherboard manual.

If the fan came with the CPU it probably has coolant paste on it. Some choose to use that coolant paste, others choose to purchase “performance” coolant paste. If you are planning on replacing the stock paste with your own, wipe the bottom of the fan clean using a clean rag with rubbing alcohol. Apply the “performance” cooling paste to the bottom of the fan. Be aware: adding too little or too much paste can cause a CPU to operate at a higher temperature, thereby decreasing its lifespan.

I have found that mounting the CPU fan can be the most frustrating part of building a computer. Fans used to require you to put great force on the motherboard and use a screwdriver to push the fan clip into place. More than once in my experience did a screwdriver slip and pierce a motherboard! Since then, fan design has gotten much better, but it’s still a pain.

Install the memory

The memory is a snap – literally. Read in the motherboard manual which of the 4-6 memory slots is the first, usually numbered slot 0. Install your first memory stick there. If you have a second, or more, install them into the appropriate slots. Some systems require that memory be installed in pairs.

Memory can only be installed one way, so look at the “tooth” or notch in the middle of the memory chip. One side of the memory is longer than the other. Look at the memory slot on the motherboard and align the memory stick appropriately.

Put one corner of the memory into the slot and fasten the clip. Push down the other side until it snaps into place – the clip should close itself. You will need to push down with some force. Be sure to push carefully and straight down. Pushing down at an angle could break the memory or motherboard.

Repeat for each memory stick.

Putting it all in the box

It’s now time to mount the motherboard in the case. Carefully slide the motherboard onto the risers in the case. Be sure the input panel at the back of the motherboard is aligned with the rear plate. It may be necessary to bend some parts of the plate out of the way of the motherboard. Once in place start tightening down the motherboard with the appropriate screws.

Next, unpack and install the power supply. Then unpack and install the hard drive and optical drive(s) – be sure to use the correct screws that came with the case. If you have any cards to install (video, network, sound, etc). Remove the appropriate slot cover from the back of the case and slide the expansion card into the appropriate slot. Tighten down the card with the appropriate screw.


Now it’s time to wire everything together. First, run the power lines from the power supply to the motherboard, drives, and if necessary the video card. Then connect the drives to the motherboard with the cables that came with the motherboard.

Next, you’ll need to hook up the front panel of the case to the motherboard. This may include hookups for sound, USB, and firewire. Your motherboard may not support all of these hookups. Refer to the motherboard manual for where and how these wires are connected.

The most difficult part is connecting the case power and reset buttons, power and hard drive LED, and PC speaker. There is an emerging standard where all of these are included in one single block hookup – but not every case or motherboard supports this yet. Typically these hookups are tiny little two-wire jumpers that are a pain to get in place – even with the slightest fingers. Some form of needle-nose pliers can come in handy here.

Check the motherboard manual to determine the orientation of each connection. All of these connections should be oriented the same way. Each wire has a positive and a negative and should be appropriately marked as such. If the wires or blocks are not marked, the colored wire is usually the active (+) and the white wire is usually the passive (-). If you get everything connected and plugged in, but the power button, reset button, or hard drive/power LEDs don’t work – that usually means they’re not connected properly and should be flipped 180°.

Lastly, connect any case fans, the CPU fan, and the power supply fan (if applicable) to the motherboard. Check the manual for connection locations.


At this point every internal part should be connected, installed, and tightened down. You’re now ready to connect your peripherals and power on the computer.

If your computer doesn’t power on properly check the power button connection and be sure the power supply is correctly connected to the motherboard. There may also be a power switch on the back of the power supply that needs to be flipped for power to be sent to the motherboard.

Your computer should now be booting up. All that’s left is to configure the bios (which may not be necessary. The motherboard should pick up all of the correct CPU settings and you should be able to use the system immediately, without any bios changes) and install an operating system (you may need to change the boot order in the bios to get the system to boot off the DVD drive).


It sounds like a lot of work – but believe me, it’s well worth it. You can usually build a high-end computer for half of what it would cost to purchase from a major retailer. It’s a fun project and helps you learn exactly what makes a PC tick. When the computer starts slowing down or needs more storage space, you’ll know exactly how to install more memory or add another hard drive. Building your computer is a very rewarding experience.