ATI key motherboard designer John Bruno told us that a single rail PSU is better than a multi rail PSU. He reported that ATI had some issues with multi rail PSUs while all of the single rail 500 W + PSUs were running fine. It turns out that both OCZ Power stream 600 W PSU and Akasa
After reading this and a email to HIS with the question of what PSU to use with my X1900XTX IceQ3.....all suggest a name brand manufacture (cause penny pinching on a PSU is reckless). So I decided on Enermax. As for the particular specs (in my situation) 460W was fine so long as it was a single +12V rail. Dual +12V are not always the best way to go. HIS tech support told me that Dual +12V is best suited for those on the other side of the pond for reasons I didn't quite understand (something about the votage difference). They said single +12V rail PSU was safe and my CPU and the few drives I have would get all they needed without depriving my 1900XTX.