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 desktop. The cards were tested under load running Oblivion at 1024x768 resolution with the game's "high quality" settings, 4X AA, and 16X anisotropic filtering. We loaded up the game and ran it in the same area where we did our performance testing.

The Radeon HDs draw a little bit more power at idle than the GeForce cards, but they make up for it by pulling less juice when running Oblivion. Impressively, although the RV630 is a larger chip with more transistors, it draws less power than the G86.

Noise levels and cooling
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 Zalman CNPS9500 LED 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.

Our noise testing reveals two clear results, which our ears picked up quite readily, as well. First, the Radeon HD 2600 Pro is the loudest card of the lot, both at idle and under load. That little cooler is a bit overmatched for the RV630 GPU. Second, the largest cooler of the lot, on the 2600 XT, is also the quietest overall. The 2600 XT's cooler is much larger than the GeForce 8600 GT's, and true to form, that translates into less noise.