Re: new psu
550W doesnt surprise me. It'd be a good psu size with a bit of overhead. That said, I think ati says 450W with that gpu.
Its unfortunate you only want tiger as they dont have great selectionsd.
However, the cx500 is the best/inexpensive option, but its oly under 50 if you count the mir.
If you look at a 500 zand a 550 of the same price, yo'll see the Amps on the 12V are the same. Basically they both put out the same power.
i'd suggest bumping your budget $15 and getting a better 500W.
Foldie = i7 950@ 4.0Ghz Gigabyte x58a-ud3r EVGA 970 SC Corsair H100 Corsair hx520 3x2gb OCZ Gold Corsair 650D
Woohoo = L5639 @3.1Ghz EVGA SR-2 gtx 260-216 Hyper 212+ Corsair 1050hx 6x2gb Corsair XMS3 Blackhawk Ulra
Alienware 18 - SLI 770M 4700mq 16Gig