Not really overclocking related, but interesting none-the-less. Finding it rather amusing to see the GTX580 in between multi-GPU cards!
With their recent generation GPUs, NVIDIA and then AMD have attached more importance to offering lower consumption cards (even high-end), with the exception of 3D load scores that is. Most recent cards score somewhere in the order of 20 to 30 watts when not in 3D mode.
Energy consumption in load peaked with the Radeon HD 4870 X2, which still has the doubtful record of being the highest consumption card to date. NVIDIA did get dangerously close however with the GeForce GTX 480 and 580, mono-GPU solutions which manage to consume up to 309 watts in extreme load!
Conscious of the bad publicity of having a graphics card that draws too much power, both NVIDIA and AMD have introduced solutions that aim to limit the energy consumption in load to more reasonable levels.
With the GTX 570 and 580, NVIDIA has introduced components which allow drivers (but not the GPU directly) to monitor GPU consumption. There’s no overall monitoring and the driver simply activates its system (lowering of clocks beyond certain energy consumption levels) in the latest versions of Furmark and OCCT (the version of Furmark that we’re using wasn’t detected), that’s to say in the extreme load tests used by testers to measure energy consumption. In practice, the NVIDIA system ends up placing limitations on such software that stops you from using it rather than maintaining energy consumption within a well-defined thermal envelope.
AMD has also integrated a mechanism, PowerTune, that aims to limit the energy consumption of cards. In contrast to the NVIDIA system, PowerTune is controlled by the GPU and is a global system. Beyond a limit fixed by AMD that would imply 200W or 250W on the Radeon HD 6950 and 6970 in the worst cases, the GPU lowers its clocks. You can modify this limit via the Catalyst Overdrive dashboard. In practice, on a Radeon HD 6950, if you increase the limit, you go from 159/161 watts on 3Dmark/FurMark to 166/185 watts and from 211/214 to 245/271 watts on the Radeon HD 6970.