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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  • Roland00Address - Wednesday, December 15, 2010 - link

    1) The architecture article is something that can be written before hand, or written during benching (if the bench is on a loop). It has very little "cramming" to get out right after a NDA ends. Anand knows this info for a couple of weeks but can't discuss it due to NDAs. Furthermore the reason anandtech is one of the best review sites on the net is the fact they do go into the architecture details. The architecture as well as the performance benchmarks is the reason I come to anandtech instead of other review sites as my first choice.

    2) The spelling and grammar errors is a common thing at anandtech, this is nothing new. That said I can't complain for my spelling and grammar is far worse than Ryan's.

    If you don't like the style of the review go somewhere else.
    Reply
  • Ryan Smith - Wednesday, December 15, 2010 - link

    1) That's only half true. AMD told us the basics about the 6900 series back in October, but I never had full access to the product information (and more importantly the developers) until 1 week ago. So this entire article was brought up from scratch in 1 week.

    It's rare for us to get too much access much earlier than that; the closest thing was the Fermi launch where NVIDIA was willing to talk about the architecture months in advance. Otherwise that's usually a closely held secret in order to keep the competition from having concrete details too soon.
    Reply
  • Dracusis - Wednesday, December 15, 2010 - link

    Neither the AMD 6xxx series or Nvidia's 5xx series have been added. Would like to see how my 4870x2 stack up against this latest generation and weather or not it's worth upgrading. Reply
  • Makaveli - Wednesday, December 15, 2010 - link

    The Canadian pricing on these cards are hilarious.

    Ncix is taking preorder for the 6970 at $474.

    While they sell the 570 for $379.

    Can someone explain to me why I would pay $100 more for the radeon when the 570 gives equal performance?

    Are these retailers that retarded?
    Reply
  • stangflyer - Thursday, December 16, 2010 - link

    They will price the 6950/6970 high for a few days to get the boys that bleed red and have to have the new cards right away to pay top dollar for the card.

    After a week they will probably be about the same price.
    Reply
  • Ryan Smith - Thursday, December 16, 2010 - link

    Bench will be up to date by the start of next week. Reply
  • Paladin1211 - Thursday, December 16, 2010 - link

    Whats wrong with you rarson? Do you even know whats the difference between "Graphics card review", "Performance review", "Performance Preview"? I dont know how good your grammar and spelling are, but they dont matter as long as you cant understand the basic meaning of the words.

    Most of the sites will tell you about WHAT, but here at AnandTech, you'll truly find out WHY and HOW. Well, of course, you can always go elsewhere try to read some numbers instead of words.

    Keep up the good works, Ryan.
    Reply
  • Belard - Thursday, December 16, 2010 - link

    The 3870 and 3850 were the TOP end for ATI, as was the 4800 and the 5800. Their relationship of model numbers do not have anything to do with the status of Nvidia.

    When the 3870 was brand new, what was the HIGHEST end card ATI had back then? Oh yeah, the 3870!

    4800 is over the 3870, easily.
    4600 replaced the 3800

    The 5800s replaces the 4800s... easily.
    the 5700s kind of replaced the 4800s.

    The 6800s replaces the 5700 & 5800s, the 6900s replace the 5800s, but not so much on performance.

    I paid $90 for my 4670 and a much better value than the $220 3870 since both cards perform almost the same.
    Reply
  • AmdInside - Thursday, December 16, 2010 - link

    I can't think of a single website that has better hardware reviews, at least for computer technology than Anandtech. Ryan, keep up the great work. Reply
  • George.Zhang - Thursday, December 16, 2010 - link

    BTW, HD6950 looks great and affordable for me. Reply

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