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 UT3 at 2560x1600 resolution, using the same settings we did for performance testing.
Note that the SLI configs were, by necessity, tested on a different motherboard than the single cards, as noted in our testing methods section. Also, because it required extra help, the three-way SLI system was tested with the PC Power & Cooling Turbo-Cool 1200 power supply. The other systems were tested with a Silencer 750W PSU.
We have breached the 600W mark! Whoa. That's like 26 swirly bulbs of "60W equivalent" output. Obviously, a three-way SLI rig will spin the meter. Even at idle, it draws over 400W.
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 12" 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.
Unfortunately—or, rather, quite fortunately—I wasn't able to reliably measure noise levels for most of these systems at idle. Our test systems keep getting quieter with the addition of new power supply units and new motherboards with passive cooling and the like, as do the video cards themselves. I decided this time around that our test rigs at idle are too close to the sensitivity floor for our sound level meter, so I only measured noise levels under load.
I did, however, make an exception for the three-way SLI system with its 1200W PSU, which creates enough noise to register 52.6 dB on the meter at idle, even though the rest of the systems were at or under 40 dB.
The three-way system was also the noisiest of the bunch when running a game. Some of that noise comes from its relatively loud PSU, but subjectively, the coolers on the three 8800 Ultras sandwiched together certainly seemed to be contributing to the cacophany, as well.
GPU temperatures
Per your requests, I've added GPU temperature readings to our results. I captured these using AMD's Catalyst Control Center and Nvidia's nTune Monitor, so we're basically relying on the cards to report their temperatures properly. In the case of multi-GPU configs, well, I only got one number out of CCC. I used the highest of the numbers from the Nvidia monitoring app. These temperatures were recorded while running UT3 in a window.
Cramming three of these cards together raises the temperature quite a bit, which helps explain why the coolers generate more noise.
