Choosing PSU/RAM and help with my new PC

[Georgi Denev]

So i am making myself a Gaming PC (for the first time). And i need help with my PSU/RAM/Case and comments/ideas/criticism on the build.
CPU:
Intel Core i5-3570 Quad-Core Processor 3.4 GHz
Motherboard:
AsRock Z77 Extreme4 Motherboard
GPU:
AMD Radeon HD 7870 2GB GDDR5

My budget is 1000$

 

[Tradesman1]

Not sure what all you'll be doing with it, but if no SLI/XFire the could go about a 5-550 PSU, not sure of your budget, but I'd look at this as sort of entry

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153172

for DRAM, for most folks 8GB is enough so would suggest 2x4GB prob 1600 with CL of 8 or 9, or if you want 16GB the specs above but in 2x8gb