Psu is fine, it powers the gtx280 in the second slot no problem? any more ideas ??
Quote Originally Posted by cmthomson View Post
Just a guess: sounds to me like one of the 12V rails on your power supply is overloaded and shutting down. You may need a bigger/better supply for this graphics card.

Really wild guess: did you attach the auxiliary 6-pin power cable to the video card? This card draws more than 75W which is the maximum the PCI-e connector will supply.