• What
    is this?
    You've landed on the AMD Portal on AnandTech. This section is sponsored by AMD. It features a collection of all of our independent AMD content, as well as Tweets & News from AMD directly. AMD will also be running a couple of huge giveaways here so check back for those.
    PRESENTED BY

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
POST A COMMENT

167 Comments

View All Comments

  • 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

Log in

Don't have an account? Sign up now