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Tweaking PowerTune

While the primary purpose of PowerTune is to keep the power consumption of a video card within its TDP in all cases, AMD has realized that PowerTune isn’t necessarily something everyone wants, and so they’re making it adjustable in the Overdrive control panel. With Overdrive you’ll be able to adjust the PowerTune limits both up and down by up to 20% to suit your needs.

We’ll start with the case of increasing the PowerTune limits. While AMD does not allow users to completely turn off PowerTune, they’re offering the next best thing by allowing you to increase the PowerTune limits. Acknowledging that not everyone wants to keep their cards at their initial PowerTune limits, AMD has included a slider with the Overdrive control panel that allows +/- 20% adjustment to the PowerTune limit. In the case of the 6970 this means the PowerTune limit can be adjusted to anywhere between 200W and 300W, the latter being the ATX spec maximum.

Ultimately the purpose of raising the PowerTune limit depends on just how far you raise it. A slight increase can bring a slight performance advantage in any game/application that is held back by PowerTune, while going the whole nine yards to 20% is for all practical purposes disabling PowerTune at stock clocks and voltages.

We’ve already established that at the stock PowerTune limit of 250W only FurMark and Metro 2033 are PowerTune limited, with only the former limited in any meaningful way. So with that in mind we increased our PowerTune limit to 300W and re-ran our power/temperature/noise tests to look at the full impact of using the 300W limit.

Radeon HD 6970: PowerTune Performance
PowerTune 250W PowerTune 300W
Crysis Temperature 78 79
Furmark Temperature 83 90
Crysis Power 340W 355W
Furmark Power 361W 422W

As expected, power and temperature both increase with FurMark with PowerTune at 300W. At this point FurMark is no longer constrained by PowerTune and our 6970 runs at 880MHz throughout the test. Overall our power consumption measured at the wall increased by 60W, while the core clock for FurMark is 46.6% faster. It was under this scenario that we also “uncapped” PowerTune for Metro, when we found that even though Metro was being throttled at times, the performance impact was impossibly small.

Meanwhile we found something interesting when running Crysis. Even though Crysis is not impacted by PowerTune, Crysis’ power consumption still crept up by 15W. Performance is exactly the same, and yet here we are with slightly higher power consumption. We don’t have a good explanation for this at this point – PowerTune only affects the core clock (and not the core voltage), and we never measured Crysis taking a hit at 250W or 300W, so we’re not sure just what is going on. However we’ve already established that FurMark is the only program realistically impacted by the 250W limit, so at stock clocks there’s little reason to increase the PowerTune limit.

This does bring up overclocking however. Due to the limited amount of time we had with the 6900 series we have not been able to do a serious overclocking investigation, but as clockspeed is a factor in the power equation, PowerTune is going to impact overclocking. You’re going to want to raise the PowerTune limit when overclocking, otherwise PowerTune is liable to bring your clocks right back down to keep power consumption below 250W. The good news for hardcore overclockers is that while AMD set a 20% limit on our reference cards, partners will be free to set their own tweaking limits – we’d expect high-end cards like the Gigabyte SOC, MSI Lightning, and Asus Matrix lines to all feature higher limits to keep PowerTune from throttling extreme overclocks.

Meanwhile there’s a second scenario AMD has thrown at us for PowerTune: tuning down. Although we generally live by the “more is better” mantra, there is some logic to this. Going back to our dynamic range example, by shrinking the dynamic power range power hogs at the top of the spectrum get pushed down, but thanks to AMD’s ability to use higher default core clocks, power consumption of low impact games and applications goes up. In essence power consumption gets just a bit worse because performance has improved.

Traditionally V-sync has been used as the preferred method of limiting power consumption by limiting a card’s performance, but V-sync introduces additional input lag and the potential for skipped frames when triple-buffering is not available, making it a suboptimal solution in some cases. Thus if you wanted to keep a card at a lower performance/power level for any given game/application but did not want to use V-sync, you were out of luck unless you wanted to start playing with core clocks and voltages manually. By being able to turn down the PowerTune limits however, you can now constrain power consumption and performance on a simpler basis.

As with the 300W PowerTune limit, we ran our power/temperature/noise tests with the 200W limit to see what the impact would be.

Radeon HD 6970: PowerTune Performance
PowerTune 250W PowerTune 200W
Crysis Temperature 78 71
Furmark Temperature 83 71
Crysis Power 340W 292W
Furmark Power 361W 292W

Right off the bat everything is lower. FurMark is now at 292W, and quite surprisingly Crysis is also at 292W. This plays off of the fact that most games don’t cause a card to approach its limit in the first place, so bringing the ceiling down will bring the power consumption of more power hungry games and applications down to the same power consumption levels as lesser games/applications.

Although not whisper quiet, our 6970 is definitely quieter at the 200W limit than the default 250W limit thanks to the lower power consumption. However the 200W limit also impacts practically every game and application we test, so performance is definitely going to go down for everything if you do reduce the PowerTune limit by the full 20%.

Radeon HD 6970: PowerTune Crysis Performance
PowerTune 250W PowerTune 200W
2560x1600 36.6 28
1920x1200 51.5 43.3
1680x1050 63.3 52

At 200W, you’re looking at around 75%-80% of the performance for Crysis. The exact value will depend on just how heavy of a load the specific game/application was in the first place.

PowerTune, Cont Another New Anti-Aliasing Mode: Enhanced Quality AA
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  • henrikfm - Wednesday, December 15, 2010 - link

    The right numbers for these cards considering the performance:

    6970 -> 5875
    6950 -> 5855
    Reply
  • flyck - Wednesday, December 15, 2010 - link

    Anand also tested with 'outdated' drivers. It is ofcourse AMD fault to not supply the best drivers available at launch though. But anand used 10.10, Reviews that use 10.11 like HardOcp see that the 6950 performance equally or better than 570GTx!! and 6970 trades blows with 580GTX but is overall little slower (but faster than 570GTX).

    And now we have to wait for the 10.12 drivers which were meant to be for 69xx series.
    Reply
  • flyck - Wednesday, December 15, 2010 - link

    my bad anand tested with 10.11 :shame:
    10.12 don't seam to improve performance.

    That said, Anand would it be possible to change your graphs?
    Starting with the low quality and ending with the high quality? And also make the high quality chart for single cards only. Now it just isn't readable with SLI and crossfire numbers through it.

    According to your results 6970 is > 570 and 6950~570 but only when everything turned on.. but one cannot deduct that with the current presentation.
    Reply
  • Will Robinson - Wednesday, December 15, 2010 - link

    $740 for HD6970 CrossfireX dominates GTX580 SLI costing over $1000.
    That's some serious ownage right there.
    Good pricing on these new cards and solid numbers for power/heat and noise.
    Seems like a good new series of cards from AMD.
    Reply
  • prdola0 - Wednesday, December 15, 2010 - link

    No, you're wrong. Re-read the graphs. GTX580 SLI wins most of the time. Reply
  • softdrinkviking - Wednesday, December 15, 2010 - link

    By a small average amount, and for ~$250 extra.
    Once you get to that level, you're not really hurting for performance anyway, so for people who really just want to play games and aren't interested in having the "fastest card" just to have it, the 6970 is the best value.
    Reply
  • Nfarce - Wednesday, December 15, 2010 - link

    True. However AMD has just about always been about value over an all out direct card horsepower war with Nvidia. Some people are willing to spend for bragging rights.

    But I'm a little suspect on AT's figures with these cards. Two other tech sites (Toms Hardware and Guru3D) show the GTX 570 and 580 solidly beating the 6950 and 6970 respectively in the same games with similar PC builds.
    Reply
  • IceDread - Friday, December 17, 2010 - link

    You are wrong. HD 5970 in crossfire wins over gtx 580 sli. But anandtech did not test that. Reply
  • ypsylon - Wednesday, December 15, 2010 - link

    A lot of people were anxious to see what AMD will bring to the market with 6950/6970. And once again not much. Some minor advantages (like 5FPS in handul of games) is nothing worth writing or screaming about. For now GTX580 is more expensive, but now with AMD unveiling new cards nVidia will get really serious about the price. That $500 price point won't live for long. I expecting at least 50$ off that in the next 4-6 weeks.

    GTX580 is best option today for someone who is interested in new VGA, if you do own right now 5850/5870/5970 (CF or not) don't even bother with 69[whatever].
    Reply
  • duploxxx - Wednesday, December 15, 2010 - link

    at that price point a 580 the best buy, get lost. The 580 is way over prized for the small performance increase it has above 570-6970 not to mentioning the additional power consumption. Don't see any reason at all to buy that card.

    Indeed no need to upgrade from a 58xx series but neither would be to move to a nv based card.
    Reply

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