To this day I still cannot believe how many people ask me why and how I build my computers rather than buy pre assembled. Every one I tell just how easy it is they usually ask me to help them buy parts and where they would be able to purchase the components. Well here I am going to explain to you just how easy it is to build your self a good computer. The first is finding a place to get your parts and a simple search will find you many sites to purchase and some computer and over clocking forums may have a whole section dedicated to selling older parts. Now that you have found a place to purchase from you can start researching parts and deciding on parts. Generally I start from the CPU so that I don't find a mobo that I want that ends up not match the CPU socket and the higher the GHz the quicker the CPU.
After the CPU I jump straight to finding a motherboard and start reading reviews and specs of many different boards. Now that the mobo is taken care of you can jump from here but lets start at the ram. Ram or memory type will be listed in the motherboards specs as well as the maximum amount that is supported by the mobo. Next you can start looking for a video card and make sure you do research on the card so you may know if is the right card for you're needs and how many watt power supply you need to buy. If you are building a computer for just browsing the web and playing flash games it would be impractical for you to spend $1000 or more for dual graphics cards or even $500 or more for a higher end card. Purchasing hard drives make sure the drives are compatible with the connectors on your motherboard and the amount of storage space you need and you can have multiple drives connected if you need to have massive amounts of storage.
Next looking at cd/dvd/blue ray drive there is a good selection of drives and make sure you research what you are looking at getting and make sure it does every thing that you need it to do. Next if you want one or if the on board seams to be junk you can look at getting a sound card and then you can look into getting speakers and a good pair of headphones. Next look for a case that best suits what you need, motherboard format, how many fan slots, fan size, water cooling, hard drive bays, psu mounting spot, number of hard drive bays, and price. IF you are wanting to build a really high end gaming computer you can look into doing water cooling as a quiet and more efficient cooling method but more expensive. If you choose not to go with water cooling you can always purchase after market heat sinks for you CPU and GPU and if you chose to you should also purchase some arctic silver and a manual fan controller for your gpu cooler as you may be unable to control the fan speed from software.
If you choose a aftermarket cooler you should make sure that you have enough space on the board for any other devices you are going to putting in any other slot like a sound card or a second video card. Next you should look at a power supply by looking at the components you have decided to purchase and determine how many watts you are going to need. Finally you should look at what OS you are wanting to run windows, linux, it is up to you. Once you have your parts you can assemble every thing then from there install your os update mobo bios drivers and all other software. Make sure when first installing all hardware you connect ram before you're CPU if you have a aftermarket heat sink that sits over the ram slots. Your motherboard manual will tell you where the power and reset wires need to be connected to. Do as much research as you need before purchasing parts and if in doubt there are many forums with loads of information and plenty of good suggestions on what to get. Once you guys get into it you will find out that it is not hard at all to get your computer built and running so good luck and have fun.