Power consumption
For kicks, I whipped out my trusty watt meter and measured overall system power consumption at idle and under load (running Far Cry at 1600x1200 with 4X antialiasing and 8X aniso).

With lower clock speeds and less memory, it's no surprise that our vanilla 6800s have lower power consumption than the GT and Ultra cards. This one lines up according to clock speed: the higher the clock, the higher the power consumption.

Noise levels
Noise levels were measured using an Extech 407727 Digital Sound Level Meter. Idle and load environments were identical to those described in our power consumption tests.

Despite their lower clock speeds, our vanilla 6800s were actually noisier than the 6800 GTs. Not by much, mind you. Unfortunately, the AA6800's slightly different cooler design didn't yield lower noise levels than NVIDIA's stock cooler. Maybe there's something to sticking to the reference design after all.

Although it's certainly no Dustbuster, the eVGA Ultra's noise levels at idle and under load are higher than the rest. That should come as no surprise considering the card's higher clock speeds and meaty two-slot cooler, but it seems a little excessive to be running that loud at idle.