Quite frankly, the 8800 from Nvidia and the 2900 XT from ATI are both pigs in my opinion. They are better as a personal 250 Watt space heater. I am skipping that generation since ATI has already announced that their new 38XX line will take less than 1/2 the power, and Nvidia is rumored to doing the same thing.
Just hold tight for a bit. Think of the 2900 and 8800 lines as overclocked cards. There is no reason they should consume half the power in your entire system!!! Including your hard drives!!
-S
PS. I still run a x1900 XTX and it performs nearly as well as these power hogs, and it is last generation! When I installed the x1900 XTX, I already thought it was a power hog. Seems I was not even close to what would happen next generation. I could probably overclock my x1900 with proper cooling to get near identicle perf as the current gen with the same power consumption!
__________________

|