I'd get a seasonic or a silverstone. I know corsairs are supposedly made by seasonic, but i suspect they are more cheaply made, otherwise they would be seasonic branded.
All the more reason for a BIG single 12v rail, the gfx card, or anything for that matter, an suck as much power as they want from the 12v rail without it drooping, assuming its less than 54 amps in the case of the OP650.

I'm actually tempted with the PC Power & Cooling Silencer 750 Quad PCI-E 750W PSU when it's back in stock, looks superb![]()