Redefining TDP With PowerTune

One of our fundamental benchmarks is FurMark, oZone3D’s handy GPU load testing tool. The furry donut can generate a workload in excess of anything any game or GPGPU application can do, giving us an excellent way to establish a worst case scenario for power usage, GPU temperatures, and cooler noise. The fact that it was worse than any game/application has ruffled both AMD and NVIDIA’s feathers however, as it’s been known to kill older cards and otherwise make their lives more difficult, leading to the two companies labeling the program a “power virus”.

FurMark is just one symptom of a larger issue however, and that’s TDP. Compared to their CPU counterparts at only 140W, video cards are power monsters. The ATX specification allows for PCIe cards to draw up to 300W, and we quite regularly surpass that when FurMark is in use. Things get even dicier on laptops and all-in-one computers, where compact spaces and small batteries limit how much power a GPU can draw and how much heat can effectively be dissipated. For these reasons products need to be designed to meet a certain TDP; in the case of desktop cards we saw products such as the Radeon HD 5970 where it had sub-5870 clocks to meet the 300W TDP (with easy overvolting controls to make up for it), and in laptop parts we routinely see products with many disabled functional units and low clocks to meet those particularly low TDP requirements.

Although we see both AMD and NVIDIA surpass their official TDP on FurMark, it’s never by very much. After all TDP defines the thermal limits of a system, so if you regularly surpass those limits it can lead to overwhelming the cooling and ultimately risking system damage. It’s because of FurMark and other scenarios that AMD claims that they have to set their products’ performance lower than they’d like. Call of Duty, Crysis, The Sims 3, and other games aren’t necessarily causing video cards to draw power in excess of their TDP, but the need to cover the edge cases like FurMark does. As a result AMD has to plan around applications and games that cause a high level of power draw, setting their performance levels low enough that these edge cases don’t lead to the GPU regularly surpassing its TDP.

This ultimately leads to a concept similar to dynamic range, defined by Wikipedia as: “the ratio between the largest and smallest possible values of a changeable quantity.” We typically use dynamic range when talking about audio and video, referring to the range between quiet and loud sounds, and dark and light imagery respectively. However power draw is quite similar in concept, with a variety of games and applications leading to a variety of loads on the GPU. Furthermore while dynamic range is generally a good thing for audio and video, it’s generally a bad thing for desktop GPU usage – low power utilization on a GPU-bound game means that there’s plenty of headroom for bumping up clocks and voltages to improve the performance of that game. Going back to our earlier example however, a GPU can’t be set this high under normal conditions, otherwise FurMark and similar applications will push the GPU well past TDP.

The answer to the dynamic power range problem is to have variable clockspeeds; set the clocks low to keep power usage down on power-demanding games, and set the clocks high on power-light games. In fact we already have this in the CPU world, where Intel and AMD use their turbo modes to achieve this. If there’s enough thermal and power headroom, these processors can increase their clockspeeds by upwards of several steps. This allows AMD and Intel to not only offer processors that are overall faster on average, but it lets them specifically focus on improving single-threaded performance by pushing 1 core well above its normal clockspeeds when it’s the only core in use.

It was only a matter of time until this kind of scheme came to the GPU world, and that time is here. Earlier this year we saw NVIDIA lay the groundwork with the GTX 500 series, where they implemented external power monitoring hardware for the purpose of identifying and slowing down FurMark and OCCT; however that’s as far as they went, capping only FurMark and OCCT. With Cayman and the 6900 series AMD is going to take this to the next step with a technology called PowerTune.

PowerTune is a power containment technology, designed to allow AMD to contain the power consumption of their GPUs to a pre-determined value. In essence it’s Turbo in reverse: instead of having a low base clockspeed and higher turbo multipliers, AMD is setting a high base clockspeed and letting PowerTune cap GPU performance when it exceeds AMD’s TDP. The net result is that AMD can reduce the dynamic power range of their GPUs by setting high clockspeeds at high voltages to maximize performance, and then letting PowerTune cap GPU performance for the edge cases that cause GPU power consumption to exceed AMD’s preset value.

Advancing Primitives: Dual Graphics Engines & New ROPs PowerTune, Cont
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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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