a system equipped with
CPU: Intel Core i7-3960X @ 4.3GHz
Motherboard: EVGA X79 SLI
Hard Disk: Samsung 470 (256GB)
Memory: G.Skill Ripjaws DDR3-1867 4 x 4GB (8-10-9-26)
and gtx 660, only consume
287 watt for total power consumption while gaming
and 254 watt while stressing the graphic card with occt
So, any 400w good quality psu from well known brand (antec, corsair, seasonic, fsp, etc) will be more than enough for your system, and you'll have plenty headroom..
For example: Corsair CX430...