DaveW wrote:
What are the brand and specs of the Power Supply Unit you are using? It
sounds like the more power demanding 6800 card is being power starved by the
PSU.

It's an Antec NeoPower 480. Should be plenty.

+5V 38A
+12V1 18A
+12V2 15A
+3.3V 30A
-12V 1A
+5sb 2A

Continuous 480W
Peak 12V(1+2) 32A