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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  • MeanBruce - Wednesday, December 15, 2010 - link

    TechPowerUp.com shows the 6850 as 95percent or almost double the performance of the 4850 and 100percent more efficient than the 4850@1920x1200. I also am upgrading an old 4850, as far as the 6950 check their charts when they come up later today. Reply
  • mapesdhs - Monday, December 20, 2010 - link


    Today I will have completed by benchmark pages comparing 4890, 8800GT and
    GTX 460 1GB (800 and 850 core speeds), in both single and CF/SLI, for a range
    of tests. You should be able to extrapolate between known 4850/4890 differences,
    the data I've accumulated, and known GTX 460 vs. 68xx/69xx differences (baring
    in mind I'm testing with 460s with much higher core clocks than the 675 reference
    speed used in this article). Email me at mapesdhs@yahoo.com and I'll send you
    the URL once the data is up. I'm testing with 3DMark06, Unigine (Heaven, Tropics
    and Sanctuary), X3TC, Stalker COP, Cinebench, Viewperf and PT Boats. Later
    I'll also test with Vantage, 3DMark11 and AvP.

    Ian.
    Reply
  • ZoSo - Wednesday, December 15, 2010 - link

    Helluva 'Bang for the Buck' that's for sure! Currently I'm running a 5850, but I have been toying with the idea of SLI or CF. For a $300 difference, CF is the way to go at this point.
    I'm in no rush, I'm going to wait at least a month or two before I pull any triggers ;)
    Reply
  • RaistlinZ - Wednesday, December 15, 2010 - link

    I'm a bit underwhelmed from a performance standpoint. I see nothing that will make me want to upgrade from my trusty 5870.

    I would like to see a 2x6950 vs 2x570 comparison though.
    Reply
  • fausto412 - Wednesday, December 15, 2010 - link

    exactly my feelings.

    it's like thinking Miss Universe is about to screw you and then you find out it's her mom....who's probably still hot...but def not miss universe
    Reply
  • Paladin1211 - Wednesday, December 15, 2010 - link

    CF scaling is truly amazing now, I'm glad that nVidia has something to catch up in terms of driver. Meanwhile, the ATI wrong refresh rate is not fixed, it stucks at 60hz where the monitor can do 75hz. "Refresh force", "refresh lock", "ATI refresh fix", disable /enable EDID, manually set monitor attributes in CCC, EDID hack... nothing works. Even the "HUGE" 10.12 driver can't get my friend's old Samsung SyncMaster 920NW to work at its native 1440x900@75hz, both in XP 32bit and win 7 64bit. My next monitor will be an 120hz for sure, and I don't want to risk and ruin my investment, AMD. Reply
  • mapesdhs - Monday, December 20, 2010 - link


    I'm not sure if this will help fix the refresh issue (I do the following to fix max res
    limits), but try downloading the drivers for the monitor but modify the data file
    before installing them. Check to ensure it has the correct genuine max res and/or
    max refresh.

    I've been using various models of CRT which have the same Sony tube that can
    do 2048 x 1536, but every single vendor that sells models based on this tube has
    drivers that limited the max res to 1800x1440 by default, so I edit the file to enable
    2048 x 1536 and then it works fine, eg. HP P1130.

    Bit daft that drivers for a monitor do not by default allow one to exploit the monitor
    to its maximum potential.

    Anyway, good luck!!

    Ian.
    Reply
  • techworm - Wednesday, December 15, 2010 - link

    future DX11 games will stress GPU and video RAM incrementally and it is then that 6970 will shine so it's obvious that 6970 is a better and more future proof purchase than GTX570 that will be frame buffer limited in near future games Reply
  • Nickel020 - Wednesday, December 15, 2010 - link

    In the table about whether PowerTune affects an application or not there's a yes for 3DMark, and in the text you mention two applications saw throttling (with 3DMark it would be three). Is this an error?

    Also, you should maybe include that you're measuring the whole system power in the PowerTune tables, it might be confusing for people who don't read your reviews very often to see that the power draw you measured is way higher than the PowerTune level.

    Reading the rest now :)
    Reply
  • stangflyer - Wednesday, December 15, 2010 - link

    Sold my 5970 waiting for 6990. With my 5970 playing games at 5040x1050 I would always have a 4th extended monitor hooked up to a tritton uve-150 usb to vga adapter. This would let me game while having the fourth monitor display my teamspeak, afterburner, and various other things.
    Question is this!! Can i use the new 6950/6970 and use triple monitor and also use a 4th screen extended at the same time? I have 3 matching dell native display port monitors and a fourth with vga/dvi. Can I use the 2 dp's and the 2 dvi's on the 6970 at the same time? I have been looking for this answer for hours and can't find it! Thanks for the help.
    Reply

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