Need Help Building a Computer

i agree with this. we need things a little more detailed. maybe even talk about what you want it to look like.

The things you need:
Case
Take something you like, but it should be big enough to hold all your hardware. (I got a green Sharkoon T28)

Mainboard
Your CPU-Socket should match the CPU! (I got a board with the H77-Chip/1155-Socket)

Graphic-Card
That is one of the most important things for your Gaming-PC (I got a Radeon HD 7950)

CPU
I'd recommend a i5-3570K and not the i7.

CPUCooler
Should be silent (0.5 sone or smth like that) [Freezer XTREME Rev. 2].
DO NOT FORGET THE THERMAL COMPOUND!!

Power Supply
Take something you like, bequit! is pretty good.

HDD/SSD
As much as you need (I got a 64GB SSD and a 1 TB HDD)

RAM
Minimum 8 GB. (I'm using 8GB Corsair vengeanc)

-- Peripherals --
- Keyboard
- Mouse
- Mousepad
etc..

I paid smth around 920€ should be around 1.2k USD and I'm not too much into FPS, but in League of Legends I'll get around 200 FPS and I can play CoDMW2 with all settings on ultra.

Greetings

Those games don't require that huge " high end PC"
I don't think it will cost a lot
just goto the link Aborted gave you and tell us what you spotted, and we will tell you if it's good or not