Hey, instead of quad crossfiring those cards, which it will be since the 295x2 is already a cross fired card with duel hawaii chips on it, send one of them to me =). Just kidding on that. As Hassaan said, 1600 watts sounds about right,. though I would probably run higher if possible since they are power hungry cards. In fact, in an AMD 8-core system depending on the specs, running one with anything less than 1000 watts is pretty sketchy. In this case btw, I don't know which of those two is better. I would say the Rosewill since it is two 12v rails vs six. Decisions decisions. As a final note, your probably gonna catch a lot of microstuttering which is inherent to crossfire, so I would guess with duel 295x2's, it will be a pretty good...