This is also helpful for me. Also once you found one you think you want google it's name + review and on some review sites like hardwaresecrets or johnnyguru, they'll have opened up the innards and see who makes the guts! You want good manufactures like FSP to make the guts of your rebranded PSU (that's what the PSU game is, if you don't know. Corsair and Antec are reputable brands because they pick good manufacturers)
I have an OCZ StealthxStream II 600w and it seemed kind of iffy since first line sucked but when I looked at reviews, I was put to ease once I knew what was inside mine.
Would that power supply run this system comfortably, would it be cutting it close, or is it not enough? What if I do some overclocking?
Ultra is NOT a brand I would choose. Stick with the high quality brands. Corsair, Seasonic, PC Power and Cooling, XFX, Antec, Silverstone or Enermax. A power supply is not where you want to go cheap. A cheap unit can die and take parts with it.
You need 550-650 watts for the above listed system. If you plan on adding a second 6970 in Crossfire bump that up to 750-850w.
Totally agree with Anort3; Do n't go cheap with the PSU.
Get yourself one from the makers he lists: 650W for non overclocking, 750W if you're going to push it, modular is neater but they tend to cost more.
Nice build otherwise, though;) .