Energy consumptionWe measured the energy consumption of the graphics cards on their own. We took these readings at idle, in 3D Mark 06 and Furmark. Note that we use a version of Furmark that isn’t detected by NVIDIA. On the GeForce GTX 580/570/560 Ti, OCP is only enabled when such a piece of software is detected. However, on the GeForce GTX 590, OCP is always on and runs anyway, without having to detect the application.
NVIDIA has however added an additional tweak which consists in reducing clocks or slowing down performances when software such as Furmark is detected whatever the energy consumption level is. NVIDIA has justified this saying that it’s an additional level of security. We however suspect that this is also a way of preventing excessive consumption showing up in tests… In any case, the version we used wasn’t subject to this tweak.
Strangely, how PowerTune behaves seems to differ from one bios to the other with the Radeon HD 6990, which we imagine may be linked to the temperature of the GPU. The higher the temperature gets, the more current leakage there is, which has a direct effect on energy consumption. We can therefore imagine that AMD hasn’t fully taken this higher temperature into account and hasn’t been particularly conservative in defining the activity to energy consumption estimation ratios in the 450 watts mode.
This means there’s more of a margin, either for overclocking the GPU or in situations of extreme load as is the case with Furmark. Thus in 375W mode, we measured the GPU clock as varying from 535 to 830 MHz, with an average of 560 MHz, while in 450W mode, the GPU clock oscillated between 670 and 880 MHz, with an average of 765 MHz. The gain in performance in Furmark was therefore a little more than 20%!
The GeForce GTX 590 consumes a similar amount of energy to the Radeon HD 6990 with the 450W bios. However it consumes 370W in 3Dmark, which corresponds to NVIDIA’s gaming TDP.
We place the cards in an Antec Sonata 3 casing and measure noise levels at idle and in load. We placed the sonometer 60 cm from the casing.
NVIDIA has worked hard to keep noise levels at a reasonable level on what is a monster of a GeForce GTX 590.
Although the Radeon HD 6990 is quiet at idle, in load, it beats the record held by the GeForce GTX 480s in SLI with a reading of over 59 dB. Here the blower is running at full speed (4900 RPM).
Note that in 375W mode, noise levels vary cyclically between 52.8 dB and 59.4 dB. The blower runs at 3600 RPM at first and then, as the temperature goes up, accellerates progressively to 4900 RPM, with temperatures dropping after several tens of seconds and the fan then gradually dropping back down to 3600 RPM before the temperature starts to go up again and the cycle starts again. We therefore imagine that if your casing is well cooled, you should be able to keep the fan running at lower speeds. In any case, it’s a long way from being quiet!