We measured total system power consumption at the wall socket using an our fancy new Yokogawa WT210 digital power meter. 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 a 2560x1600 resolution with 4X AA and 16X anisotropic filtering. We test power with Left 4 Dead because we've found that this game's fairly simple shaders tend to cause GPUs to draw quite a bit of power, so we think it's a solidly representative peak gaming workload.
Well, that's not very good. At idle, the GTX 470's power draw isn't too scary, but the GTX 480 pulls more juice than the dual-GPU Radeon HD 5970. Two idle GTX 480s in SLI draw just 20W less than a Radeon HD 5850 does while running a game.
The new GeForces draw substantially more power when running a game, too, than the competing Radeons. You've gotta take power circuitry inefficiencies into account, of course, but our GTX 480 system pulls 105W more under load than the same system with a Radeon HD 5870 installed. Wow.
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 GF100 cards' higher power draw numbers translate pretty directly into higher noise level readings on our meter. In spite of some slick engineering in the GTX 480's cooler, the card is quite a bit noisier than a stock Radeon HD 5870. The only single-GPU solution that's louder is Asus' overclocking-oriented Matrix 5870 2GB, which is tuned to keep temperatures down.
I should note that I did all of my GTX 480 SLI testing with the cards installed together in adjacent PCIe x16 slots. Nvidia's reviewer's guide suggests separating the cards if possible by installing them spaced apart, but doing so would have sacrificed eight lanes of PCIe connectivity on our X58 motherboardand possibly some performance. The GTX 480 SLI config might have been quieterand slowerif I had taken Nvidia's advice.
For what it's worth, in case the graphs don't really convey this, two GTX 480s in SLI are really frickin' loud.
We used GPU-Z to log temperatures during our load testing. In the case of multi-GPU setups, we recorded temperatures on the primary card.
Looks like Nvidia has tuned its fan control profiles to achieve lower noise levels at the cost of higher GPU temperatures. The GTX 480 runs 12° hotter than the GTX 285, and the GTX 470 is a tick hotter still. With that said, Nvidia hasn't really forged any new territory. The Radeon HD 5870 runs at similar temperatures, and it gets even warmer in a CrossFire team.
We don't usually report idle GPU temperatures because they can vary quite a bit, depending on the conditions, and aren't always primarily determined by fan speed control profiles. I should point out, though, that both our GTX 470 and 480 cards tended to drop back to much lower temperatures as they idled on our open-air test bench. We didn't see the sort of constant 90° temperatures that we saw from, say, the first wave of Radeon HD 4850s.