Power consumption
We measured total system power consumption at the wall socket using an Extech power analyzer model 380803. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement.
The idle measurements were taken at the Windows Vista desktop with the Aero theme enabled. The cards were tested under load running BioShock in DirectX 10 at 2560x1600 resolution, using the same settings we did for performance testing.
Nvidia has done a nice job with the G92's power consumption. Our 8800 GT-based test system draws over 20 fewer watts at idle than any of the others tested. Under load, the story is similar. Mash up these numbers with the performance results, and you get a very compelling power efficiency picture.
Noise levels
We measured noise levels on our test systems, sitting on an open test bench, using an Extech model 407727 digital sound level meter. The meter was mounted on a tripod approximately 14" from the test system at a height even with the top of the video card. We used the OSHA-standard weighting and speed for these measurements.
You can think of these noise level measurements much like our system power consumption tests, because the entire systems' noise levels were measured, including the stock Intel cooler we used to cool the CPU. Of course, noise levels will vary greatly in the real world along with the acoustic properties of the PC enclosure used, whether the enclosure provides adequate cooling to avoid a card's highest fan speeds, placement of the enclosure in the room, and a whole range of other variables. These results should give a reasonably good picture of comparative fan noise, though.
Nvidia's single-slot coolers have too often been gratuitously small and noisy in the past year or two, but the 8800 GT is different. This may be the quietest single-slot cooler we've ever tested (save for the passive ones), and it doesn't grow audibly louder under load. That's a pleasant surprise, since the thing can get very loud during its initial spin-up at boot time. Fortunately, it never visted that territory for us when runnning games.
