Noise levels
Noise levels were measured using an Extech 407727 Digital Sound Level meter placed along the edge of the motherboard 1" from the graphics card and out of the direct path of airflow. We recorded noise levels after 10 minutes idling at the Windows desktop, and again after 10 minutes rendering this stunning scene from Oblivion at 1920x1440 with 4X antialiasing and 16X anisotropic filtering, and all the in-game eye candy cranked. Cards were tested at both their default and overclocked speeds.

At idle, only a decibel separates the quietest card from the loudest. As one might expect, the overclocked cards tend to run a little louder, but the GeForce 8800 series cooler is so quiet at idle that it's hard to tell.

Things spread out a little under load, and this time it's the GTS cards that prove to be the quietest. What's particularly interesting here is that even the overclocked GTS cards are running quieter than the best of our GTX crowd. GTX noise levels are reasonably consistent at idle, regardless of whether the cards are overclocked.

Power consumption
System power consumption was tested, sans monitor and speakers, at the wall outlet using a Watts Up power meter. We used the same idle and load conditions as our noise level tests.

It turns out that some GeForce 8800 series cards draw a little less power than others. The GTS models are predictably the most frugal when it comes to power consumption, but overclocking also makes a difference.

GPU temperature
We tracked GPU temperatures using Nvidia's nTune system utility, which can log temperatures to a text file. Again, we used the same idle and load conditions as our noise level tests.

Perhaps the most striking thing about these results is the fact that none of the cards saw much of a change in GPU temperature from idle to load. That's curious to say the least, and it's not like nTune can't track changes in temperature—the app had no problem logging higher GPU temperatures when the cards were overclocked.

Since these cards are using the same graphics chips and reference coolers, we can't draw too many conclusions beyond the fact that G80 operating temperature seems to vary from chip to chip. EVGA's ACS³ cooling shroud doesn't appear to have a significant impact on GPU temperatures, either.

Update — Several readers have written in to tell us that they're seeing much higher load temperatures with GeForce 8800 series graphics cards monitored by third party apps like RivaTuner than we saw with Nvidia's nTune system utility. It appears that nTune's GPU temperature tracking isn't working properly with the GeForce 8800 series, and we've contacted Nvidia regarding the issue.