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

Benchmark Results: Cinebench R11 And PowerDirector 9

Desktop Usage: Cinebench R11

We've included average power consumption numbers, in addition to peak power consumption. There are some interesting things to note here. For one, we can see that the default values (clock speeds and voltage) for UVD mode are already optimal. We were only able to get away with a core voltage of 0.98 V for default UVD clocks, and the savings we see in return are very small. We also notice that lowering clocks without adjusting voltage does not translate to lower peak power consumption. Just look at the underclocked settings with the base voltage (1.175 V).

Running the card at DXVA clocks is good enough to offer some savings (between 3 to 9%) compared to the default stock clock. If you do have a graphics card with an adjustable voltage, there's a fairly good chance you can access additional savings (around 13 to 19%). Dropping memory clocks allows us to use a lower voltage and come up with even lower power consumption. At 500/1030 MHz and an operating voltage of 0.85 V, the Radeon HD 6970 we’re using is able to match the undervolted settings for the Radeon HD 5870.

H.264 GPU-Accelerated Encoding And Filters: PowerDirector 8

Keep in mind that the Radeon HD 5670 and 5770 are running at their UVD clocks. Both also feature hardware-accelerated decoding enabled. In contrast, hardware-accelerated decoding is only enabled when the Radeon HD 6970 is running at its default clocks (500/1375 MHz @ 1.0 V).

If you want an example of a best-case scenario, look at the H.264 and Bloom filter test results. The 6970 can finish the task in almost half of the time it takes AMD’s Radeon HD 5770 and 5670 to complete it.

The Radeon HD 6970 easily uses less power for the entire test, achieving nearly the same power levels as a Radeon HD 5770 and finishing in almost half of the time.

  • hokkdawg
    Dude, I'm now feeling a sudden urge to watch The Matrix!
  • I think, considering those people using SLi and crossfire and higher end videocards, they don't really give a gat about how much elec. they are using. They can afford to buy two expensive PCBs, why would they care about extra 5~10 bucks per month? If poeple are focused on lower power consumption, they would go for lower performance components, arent they?
  • anttonij
    I guess the most important point of this review is that you can lower the cards voltage while running at stock speed. For example I'm running my GTX 460 (stock 675/1800@1.012V) at 777/2070@0.975V or if I wanted to use the stock speeds, I could lower the voltage to 0.875V. I've also lowered the fan speeds to allow the card to run almost silently even at full load.
  • Khimera2000
    @.@ there is no apple @.@

    This is neat though :) I wonder if this article might inspire someone to make an application. Come on open source dont fail me now >.
  • Could you do comparison of "the fastest VC" vs "entry level" and then show us how much money we might end up paying each month or day?
  • the_krasno
    Manufacturers should find a way to implement this automatically, imagine the possibilities!
  • wrxchris

    I have 2 gfx cards pushing 3 displays, but I'm all for saving watts wherever I can. Our society has advanced to the point where sustainability is a very important buzzword that is widely ignored by mainstream media and many corporations, and this ignorance trickles down to the mainstream like Reaganomics. Minuscule reductions such as 30w savings across hundreds of thousands if not millions of users adds up to a significant reduction in carcinogenic emissions and saves valuable resources for future consumption.
  • delinius
    Holy crap, I watched the Matrix again just before this topic was posted..
  • neiroatopelcc
    So when playing video, you risk your amd card going into uvd mode? What models does that apply to?
    I want to know, cause for instance in a raid, I'd sometimes watch video content on another screen while waiting around for whatever there is to wait for. I already lose the crossfire performance because of window mode. I don't want to lose even more.

    Does my ancient 4870x2 support uvd?
  • jestersage
    so... for the dual bios HD6900s, I can RBE one bios with my desired settings and just choose which bios to use before I power up my PC? hmmm... interesting.