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 desktop with the Aero theme enabled. The cards were tested under load running Left 4 Dead at 2560x1600 resolution, using the same settings we did for performance testing.

Look at that. A single 5870 draws less power at idle than any other card we tested, besting even the prior champ, the GeForce GTX 285. And two 5870s in CrossFire draw less power at idle than a single Radeon HD 4890. Very nice.

The 5870 also draws the least power under load. Given its performance, the overall power efficiency is astounding.

Noise levels
We measured noise levels on our test system, sitting on an open test bench, using an Extech model 407738 digital sound level meter. The meter was mounted on a tripod approximately 8" 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. 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.

The 5870 has best-in-class acoustics at idle and the second-lowest noise level under load.

GPU temperatures
For most of the cards, I used GPU-Z to log temperatures during our load testing. In the case of multi-GPU setups, I recorded temperatures on the primary card. However, GPU-Z didn't yet know what to do with the 5870, so I had to resort to running a 3D program in a window while reading the temperature from the Overdrive section of AMD's Catalyst control panel.

The days of pushing 95°C on the GPU core are, happily, fading away. AMD adjusted its fan speed thresholds on the Radeon HD 4890, and it's stuck to the same formula here. That big Bat-cooler holds the 5870 to a more comfortable 76°, even though it's relatively quiet. And I'm pleased to report that our 5870 eventually dropped back down to 39° at idle after running this test.