I upgraded my computer...
Radeon 6870 x2 - Crossfire
PSU is 750 Wtts
Quad Core 2.83 Intel
When I play a game (i.e. Battlefield 3) the GPUs don't get, at least, the primary, hotter than 75c. and both run at approx. 85%.
Here is the odd thing. The computer is hooked up thru a battery...