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 1280x1024 with all the in-game eye candy cranked. Cards were tested at both their default and overclocked speeds.
You don't see scores for the Gigabyte cards at idle because noise levels were too low to register on our digital sound level meter, which bottoms out at 40 decibels. The second-quietest card of the lot is Asus' EN8600GTS, followed closely by MSI's budget NX8500GT. Both of those cards are much quieter than the NX8600GTS, whose dual-slot blower registered nearly 60 decibels while idling on the Windows desktop.
Firing up Oblivion doesn't change the picture much for four of our cards. Asus is still the quietest of the actively-cooled cards, and the NX8600GTS is still the loudest. Note that its noise levels don't really change at all from idle to load, either.
The big surprise here is of course the GV-NX86S256H, whose whiny tendencies make it the second-loudest graphics card of the lot. That's shocking for a graphics card sporting a "Silent Pipe 3" heatsink, but it's a testament to just how loud the buzzing gets when this card is doing its thing.
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.
The budget NX8500GT predictably pulls less at the wall outlet than the other cards, followed by the 8600 GT and then the wave of 8600 GTS cards. Power consumption is a little higher when the cards are overclocked than when they're running at stock speeds, which is understandable.
Things get really interesting under load, where the Gigabyte pulls 20W more than any other GTS card at stock speeds, and close to 40W more when overclocked. This behavior was consistent with both of the Gigabyte 8600 GTS cards we tested.
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.
At idle, the MSI NX8600GTS's noisy blower manages to keep the graphics chip cooler than any other 8600 GTS, but only by a degree over the much quieter Asus. The NX8500GT actually runs a little warmer than the 8600 cards, with the exception of the Gigabyte GTS.
Temperatures rise under load, and it's here that the NX8600GTS's blower really starts to pay off. The MSI card's GPU is close to 10 degrees cooler than that of Asus' EN8600GTS and even five degrees cooler than the NX8600GT. Of course, nothing compares to the GPU temperatures observed with the passively cooled Gigabyte, which hit 100 degrees after just 10 minutes under load on an open test bench. Toasty indeed.