How much power will I need?

[reubenno]

Hi all,
I was wondering how much power I will need in my soon to be built gaming rig.
My specs:
i5 3570k
ASRock extreme4 z77
8GB Corsair Vengeance
Antec Three Hundred Two
Disk Drive
Western digital caviar blue
Windows 7
Sapphire Radeon HD 7950 OC edition
Cooler Master Hyper 212 EVO

I have been looking at the XFX pro core 850w as I want enough power to crossfire which I may do so in the future, however I have heard, even with the crossfired GPUs, that this is still overkill.
The 750w model however is only £5 cheaper than the 850w model.
Thoughts?
Thanks

 

[InvalidError]

200W per GPU
150W for everything else

Add 30% for safety margin, minor upgrades, etc. and my recommendation would be something north of 700W from the usual suspects.

 

[reubenno]

Thanks guys. Im gonna stick with the XFX pro core 850w one as it is bronze certified and has plenty of power for me to upgrade my system.
On a side note, how well do you think this pc will run Crysis (1) and BattleField 3?
Thanks again