Curbing Your GPU's Power Use: Is It Worthwhile?

Benchmark Results: PowerDVD 9 And Desktop Idle

Hardware-Accelerated Video Playback: PowerDVD 9

Next up is power consumption during H.264 playback using CyberLink’s PowerDVD.

For this test, we swapped the Phenom II X4 955 BE for an Athlon II X2 250. At default clocks, the Radeon HD 5870's average power consumption is about 10 watts higher than the HD 5770. When we lower the operating voltage of the card’s UVD mode to 0.95 V, we are able to match the power consumption of the Radeon HD 5770.

Stop for a second and let that sink in. At the same frequencies and voltage, the power consumption of AMD’s Radeon HD 5870 is the same as a card driven by a GPU almost half of its size.

Power Consumption at Idle

Here we're interested in seeing just how big of a difference there is in idle power consumption between the clock settings we've chosen.

Remember, we're looking at measurements from a whole system drawing power from the wall. Looking at the results, it's quite clear that the Radeon HD 5870 at its default setting offers the lowest power consumption at idle. This is the reason why we wanted to maintain the default idle mode during testing.

At this point, the results speak for themselves. There is a way you can curb the power consumption of high-end GPUs. The easiest and safest way, at least on AMD’s cards, is by tricking them into running at UVD clocks. For the more adventurous, dialing-in a lower voltage for UVD mode (provided the option is available) can offer additional savings or improved performance.

How exactly do you trigger the UVD-specific clocks? You simply need a player or video codec that supports the UVD logic in these cards. Play a video that utilizes the codec, and that's it. You can even pause the video and the card will still stay in UVD mode.