OK guys, thanks for answers, so if I pick a PSU Corsair TX550M 80 PLUS Bronze High Performance Modular 550W it is enough for my current setup, right? And can I buy now a more powerfull PSU for my upgraded system, and how much more w's it chould be?
If you think you will upgrade to another 6950 soon, consider a 650W PSU. Power supplies are long term, Mobo's and video are short term in the computer world.
for twin 6950's? i'd say 700 from a good manufacturer. Droozel, how many amps does the 6950 say its needs?