A 2 cent guide to PC building.
Games need horsepower. The Processor (CPU) runs the program, it holds the important info to process in the memory (RAM), it displays the info with a Graphics card (GPU) onto the monitor. It needs power for all this, a case to hold it, and a hard drive to store the programs, Optical drive (DVD drive) to read cds/dvds, everything plugs into the motherboard.
Keyboard and mouse are duh.
The CPU is the brain, the GPU is the brawn.
Set a budget. You'll be picking which parts based off of this budget. If it's a $500 budget, you obviously cannot buy a $500 graphics card. The most expensive part in a gaming computer is the graphics card, but you pick the brain (CPU) first. Fortunately, tom's has great guides.
Gaming CPUs --- [ur;=
http://www.tomshardware.com/reviews/best-graphics-card-...] Gaming Graphics Cards[/url] ---
System Builder Marathon
The first 2 tell you Tom's Hardware's rated best buys for price tags. The last is them actually building 3 different computers, overclocking them, and benchmarking the base and overclock in a myriad of tests. They used this time a $500, $1000, and $2000 target.
Below $125 on the CPU, AMD is the only way to buy. But from $125 and up, Intel's Sandy Bridge eats the competition.
The CPU socket type must match the motherboard's type. You pick the CPU first, then you pick a motherboard to go with it. Intel's sandy bridge uses Socket 1155 <--- There is a socket type very close to this. Intel's first generation was Socket 1156. That's right. The first generation has a higher number than the second.
AMD uses the AM3 socket. They recently came out with AM3+, but the new processors (FX series) are worse than the old ones (Phenom series) (complicated). AM3+ processors will fit in with AM3. AMD is nice like that, but it's still better to match them.
After you've selected the CPU and Motherboard, you select the Memory (RAM). The motherboard will have specific memory types it will support (the new motherboards are mainly DDR3, so it's the memory speed you'll be looking at - 1066mhz, 1333mhz, 1600mhz are the main speeds out right now).
After the memory, you select the graphics card.
For the $500 they used a Radeon 6870 Graphics card ($170). A gaming computer does not often go much further below $500. You could go lower, but it gets to a point where the only thing left to cut money out of is the graphics card itself, and thus you will be losing more and more performance per dollar. I do not recommend going weaker than a 6770, or the equivalents of the earlier releases (5770/4870). You can use tom's to reference for NVidia cards.
The graphics card fits into a PCI express x16 slot in the motherboard. If he wanted more than one graphics card (which I do not recommend, but it's doable), he'd need more than 1 PCI express x16 slot. (There are 3 versions out, all of them work. 1.0, 2.0, and 3.0).
Once you select that, the next thing to choose is your power supply. These components use the large majority of power in the computer. Using benchmarks, you can see how much power these parts use. The Systems Builder Marathon has the Power and Heat section. Do not skimp on a power supply. If it's crap, it'll blow up, damaging the other parts.
After, you pick a case. It needs to be long enough to hold the graphics card, and it needs to be able to hold the motherboard. The motherboard has 2 formats it'd be in: ATX and microATX. This is merely the size of the motherboard.
Now you'd pick out the DVD drive, hard drive, and monitor. Most gamers use 2 storage drives: a hard drive to hold their programs, and a solid state drive to hold the operating system. SSD's are expensive, and don't last as long as a hard drive, but it is much faster. If the comp doesn't need to write over and over to the SSD, it will last. Operating Systems aren't exactly rewritten daily, and start up times are much faster with a SSD.
Last, but not least is the heat. A CPU generates a lot of heat. It needs a heatsink, thermal paste between the CPU and heatsink, and a fan. Most Heatsink+Fan models come with thermal paste, but you can never be too careful. Paste is very cheap, so it's good to grab a tube.
You may need a wireless adapter, or an ethernet cable for internet access.
For building the computer, it's not too complicated. You get the case, open it up. Put the motherboard stand offs on the case, screw the motherboard onto the standoffs. You slip the CPU into the socket, lining up the corners (one of the corners on the CPU and socket are marked), then close the pin on top of it to lock it in. You stick on the paste if needed to the heatsink, place it on the CPU, and screw it into its slows, then plug in the fan into the proper port on the motherboard. You stick in the RAM into the slots, then the graphics card into the PCIe slot. Then you install the hard drive/SSD, and the DVD drive. You install the power supply, and plug in the big plug into the motherboard, it's got like 20 pins, so it's obvious. You plug in the 6/8 pin auxillary from the PSU to the graphics. You plug in the power cables for the drives. Attach the SATA cables (should be included with the mobo/case) from the drives to the motherboard. Attach the fans around the case to the proper cables from the PSU. Plug in the Wireless card if you got one. Close up the case, attach the power cable from the wall to the comp, the monitor, etc.
To more directly answer your question, you could use a build that tom's built and tested, or you could check the parts list to make sure you have everything.
CPU - Heatsink
Motherboard - Memory
Graphics - PSU - Hard Drive
Optical Drive - Case - Monitor