Quote from: rjk on March 30, 2012, 12:33:50 PM

This is interesting to note. So as processes get smaller and smaller, power usage will fluctuate more and more widely based on temperature. All the more reason to have good cooling.

It definitely seems that this is the case. Even more interesting is the effect this causes when using fans. If I let the fans go too far beyond the GPU's sweet spot, I actually have to use a similar or higher fan speed to keep the GPU *hotter* (because of the additional wattage).

You certainly hit a "point of no return" though where it costs more energy to spin the fans faster vs the energy you'd save from keeping the chip (and VRMs?) cooler.

Quote from: Roadhog2k5 on March 30, 2012, 04:47:39 PM

Yep. Water FTW. About a 40 watt saving per card by going to water for my 7970's.

https://bitcointalk.org/index.php?topic=57410.msg683755#msg683755

The power savings are substantial, but it's certainly not 40 watts per card (unless you were running the cards very hot on air in the first place). My water cooled 7970 machine saves about 27 watts (DC) per card (at 36-37c). Keep in mind that some of the apparent power savings is simply from not having fans on the cards though. Some of this power to remove the heat gets consumed by the pump and radiator fans.