Energy consumptionWe did of course use our new test protocol that allows us to measure the energy consumption of the graphics card alone. 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 the stress test energy consumption limitation mechanism put into place by NVIDIA in the GeForce GTX 580 drivers.
At idle, the new Radeons draw the same amount of power as the previous generation. In load the Radeon HD 6970 is similar to the Radeon HD 5870 2GB while the Radeon HD 6950 consumes 10 to 20W more than the Radeon HD 5850.
Note however that both in 3Dmark06 and Furmark, the Radeon HD 6900s reduced their clocks (varying for example between 570 and 700 MHz instead of 880 MHz for the Radeon HD 6970), something we don’t understand as the limit is supposed to be between 250 and 200W and not 210 and 160W as seems to be the case in these applications. Are we to think that AMD has added an additional limitation for certain applications? That they have done so on those used by testers to measure energy consumption? Is it possible that PowerTune might be mis-estimating the true power consumption? We haven’t had any answers from AMD yet…
We place the cards in an Antec Sonata 3 casing and measure noise levels at idle and in load. We placed the sonometer 60cm from the casing.
Although the Radeon HD 6900s are quiet at idle, in load they’re noisier than the previous generation cards. Their fans are also set up to increase in speed in steps, which is a more annoying system. Here are the variations we noted in our tests:
HD 6950: 44.6 dB -> 47.1 dB
HD 6970: 47.6 dB -> 48.9 dB
HD 6950 CFX: 52.7 dB -> 54.1 dB
HD 6970 CFX: 53.7 dB -> 56.4 dB
Of course we retained the highest value across the spread. At the end of the day, then, NVIDIA has managed to turn the situation to its advantage, expecially in SLI where two GeForce GTX 570s make a lot less noise than two Radeon HD 6870s.