What PSU should I get for this custom build?

[Mac807]

As in, 620 W, 720 W blah blah blah.

CPU: Intel i7-3770 Core i7 Processor, 3.4GHz, LGA1155, Quad Core 8 Threads, 8M Cache, Intel Turbo Boost Technology (up to 3.9GHz), 22nm, with fan

Motherboard: ASRock Z77 PRO4-M MB, LGA 1155, Intel Z77, 4x DDR3, D-Sub, DVI-D, HDMI, 7.1 CH, GbLAN, SATA3, USB3.0, Quad CrossFireX, PCIE3.0, RAID, mATX

Ram: Corsair 8GB (1x8GB) DDR3 1333MHz Unbuffered CL9 DIMM

Graphics Card: RADEON HD7970

HDD: CAVIAR GREEN/1TB/IntelliPower/SATA3/64 MB/3.5

Optical Drive: Blu-Ray WRITER/14X BD-WRITE/16X DVDRW/SATA/OEM

And my case, if it matters (I have no knowledge of computers, a friend helped me make this build)

Case: Antec TWELVE HUNDRED - The Unbeatable Black Gaming Case with More Cooling, More Capacity, More Quality, No PSU

Thanks in advance

 

[butremor]

Haha lol, i came here to answer about psu but gonna do a lot more.
First off, you just wasting money getting z77 mobo to that CPU. You're better off with H77 mobo.
Also, it'd be tter to get 2x4GB stick of 1600 MHz.
Caviar green is just last HDD i woud choose, you're better off with Black or Blue for that matter.

And, as for PSU, get a quality PSU from Antec, Seasonic, XFX, Corsair or PC Power and Cooling, Silverstone. You don't need no more than 650W psu, preferably 80 Plus gold or if you want save a little then 80 plus bronze

 

[Mac807]

Haha lol, i came here to answer about psu but gonna do a lot more.
First off, you just wasting money getting z77 mobo to that CPU. You're better off with H77 mobo.
Also, it'd be tter to get 2x4GB stick of 1600 MHz.
Caviar green is just last HDD i woud choose, you're better off with Black or Blue for that matter.

And, as for PSU, get a quality PSU from Antec, Seasonic, XFX, Corsair or PC Power and Cooling, Silverstone. You don't need no more than 650W psu, preferably 80 Plus gold or if you want save a little then 80 plus bronze

Huh, you just raised more questions

What would happen if I stick with z77? Would it just be crappy crappiness for me?

Also, you made me think about this build my friend pretty much made for me. Should I be able to play Battlefield 3 (for example) on medium graphics without any trouble? He promised me I could, but I'm not exactly sure. Not good with computers, so I usually turn to him.

Final question: How would the 2x4GB stick help out this build? My friend is offline so I can't really rely on him to answer these questions for me, sorry.

If I'm being a pest, I do apologize.

 

[butremor]

YOu see z77 is made for overcloking and that CPU in not overclockable so you'd be just wasting money on mobo on features you would never use.
Also if your primarily usage is gaming you don't even need that CPU, i5 is fine , coz i7 brings no benefits to gaming.
As for the two sticks it just is. Is better for PC load splitting.
If you don't plan on overclocking and use PC for gaming then this build is just for you , and there' is no need to spend more.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3470 3.2GHz Quad-Core Processor ($149.99 @ Microcenter)
Motherboard: ASRock H77 Pro4/MVP ATX LGA1155 Motherboard ($87.55 @ Newegg)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($39.99 @ Amazon)
Storage: Western Digital Caviar Black 1TB 3.5" 7200RPM Internal Hard Drive ($93.99 @ SuperBiiz)
Video Card: Sapphire Radeon HD 7950 3GB Video Card ($309.99 @ Newegg)
Case: Cooler Master HAF 912 ATX Mid Tower Case ($49.49 @ SuperBiiz)
Power Supply: SeaSonic 520W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($69.99 @ Newegg)
Optical Drive: Samsung SH-222BB/BEBE DVD/CD Writer ($17.99 @ CompUSA)
Total: $818.98
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2012-11-18 07:04 EST-0500)

 

[Mac807]

Best answer selected by Mac807.