Look at the original post, he has a 750w Corsair.
Oh that's fine.
For 78xx series cards don't buy sapphires, they have very cheaply made low quality PCB and low end ceramic capicators that can't control power in to the GPU, this causes blackscreens if too much load is put on them(namely, gaming).
Really? I have two Sapphires in my system and they work fine.