This site bit-tech.net | Review - Nvidia GeForce GTX 295 1,792MB & Quad SLI says dual gtx295 with a OC'ed core i7 had a peak power usage of 735.5watts.
So personally I would grab something around 850 watts or more to give a little room if I was building a system like that.
So personally I would grab something around 850 watts or more to give a little room if I was building a system like that.