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 cards were plugged into a motherboard on an open test bench.

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.

Although the GTS 512 performs nearly as well as the GeForce 8800 GTX, its power draw is much lower. This is solid improvement on the power-performance front—and nothing less than we expected from a card based on the G92 GPU.

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.

Few cards stand out from the pack here, and that's generally a good thing, since they're almost all nice and quiet. The big exceptions are the GeForce 7900 GS and the Radeon HD 2900 XT, which become noisy when running a game. The GTS 512's cooler doesn't suffer that fate.

Then again, neither does the GeForce 8800 GT. One thing's worth noting, though, before we move on: we tested noise levels on an open test bench. I suspect that, when placed into a hot PC case, the GTS 512's dual-slot cooler and rear exhaust will lend itself to lower noise levels quite a bit better than the single-slot cooler on the GeForce 8800 GT. As a rule, if we don't mind sacrificing the extra expansion slot, we tend to prefer dual-slot coolers for this reason.