I believe I have 850 watt PSU that can handle a XFX Radeon HD 6990 4 GB GPU or a XFX Radeon HD 7970 (4 GB?) inside the Core i7 980x 2010 PC. Then I can put the Radeon HD 5970 that was originally in the Core 2 Quad 9550, back inside it. I expect the Radeon HD 7970 to have a faster frames per second, but it really comes down to $450 price point by mid-December.
The point of this is to own two DirectX 11 GPUs. The Playstation Vita would make an okay Birthday present. I would buy some games for it (Final Fantasy, mainly RPGs).
Tom's Hardware review