AMD's Radeon HD 5000-Series: Measuring Power Efficiency

Measuring Power Consumption: Let's Recap

What do these numbers tell us? First, the obvious: if you’re running an general-purpose application capable of utilizing your GPU, you aren’t going to load it down the same way you would if it were a game. This is why power measurement results in these scenarios don't yield the same elevated numbers seen in a more taxing benchmark like FurMark. As expected, they fall somewhere between idle and full load values we generally see in graphics cards reviews. But by how much? That naturally depends on the degree to which they utilize the GPU.

Here's a handy table with all the values from the various tests.

785Radeon 2900 XTRadeon HD 5670Radeon HD 5770Radeon HD 5870 1 GBRadeon HD 5870 2 GB
Crysis @ 1920x1080120
Adobe Photoshop CS4120
Cinebench R11 OpenGL Test132

*Peak Power Consumption in Watts

Of course, these applications don't just differ in GPU utilization, but also other resources as well (CPU, RAM, and hard disk), so those factors have to be taken into account, too. However, they affirm the claim that GPUs don't consume peak power numbers every time they're used.

The results above are quite interesting. Cinebench R11 actually pushes the processor more than Crysis. We can see this from the higher base system power consumption with Cinebench (121 vs. 132 W). Factor in that higher base system power consumption and you'll see that the actual power consumed by the graphics card is still lower in Cinebench than Crysis.

If we take out the base system's power consumption, the table above ends up more like the one below. Granted, there's some overlap in these numbers, since we do not know exactly how much power the integrated graphics consumes.

Radeon 2900 XTRadeon HD 5670Radeon HD 5770Radeon HD 5870 1 GBRadeon HD 5870 2 GB
Crysis @ 1920x1080187
Adobe Photoshop CS473
Cinebench R11 OpenGL Test100

*Peak Power Consumption attributed to each graphics cards in Watts

These numbers are important because they suggest the power draw we can realistically expect out of these cards when used in non-gaming/graphics applications. We now know just how much power is actually consumed, rather than just knowing it falls somewhere between idle and full load. We can also see the difference compared to the base system's power consumption. Should a graphics card with better power management comes along, we can point out the differences, and by just how much it improves.

Second, we've learned how managing power for different kinds of workloads really helps keep total power consumption under control. This can be seen from the PowerDVD results with the Radeon HD 5670. During H.264 playback, the Radeon HD 5670 hardly consumes more power than the integrated Radeon HD 3300, thanks to both processors’ UVD blocks. That's very efficient power management, which is even remarkable if we compare both chips side-by-side.

Another example can be seen in the Radeon HD 5870 1 GB. Running at UVD clocks (instead of full–speed) in PowerDirector allows the board to consume only 15 to 21 W more than the Radeon HD 5770. If it were to run at full speed, power consumption would be much higher.

Third, we were able to measure total power consumption. This kind of measurement can be done with similar applications, where the GPU is used to run a task completed in a certain amount of time. It’s useful in determining which graphics card offers the best performance and power consumption in that specific application. In this case, we were able to use PowerDirector. After testing, only 2 to 3 Wh separates the four Radeon HD 5000–series boards. That's quite an engineering feat.

The important element here is balance--a balance between performance and power consumption. The additional performance from the faster cards helps them finish the task and return to idle mode quickly. Overall consumption is still low enough so that we don't end up using significantly more power. It's doubtful we could possibly be aware of this just by looking at idle and full load power consumption numbers. In fact, this is the same type of comparison we like to make when looking at processors, but we’ve never really applied the same principles to graphics.

In more traditional graphics workloads, that same performance headroom benefits gamers who want higher frame rates or the ability to use slightly higher resolutions. Undoubtedly, you will be able to play Crysis at higher frame rates with the Radeon HD 5770 compared to the HD 5670. The same also applies to AMD’s Radeon HD 5870, which allows you to enjoy more demanding settings than the HD 5770.

Create a new thread in the US Reviews comments forum about this subject
This thread is closed for comments
Comment from the forums
    Your comment
    Top Comments
  • Lutfij
    ^ nvidia would loose at this battle. period.
  • tony singh
    Very innovative article tom keep it up!! Similar article consisting of various cpus would be really useful.
  • Other Comments
  • tony singh
    Very innovative article tom keep it up!! Similar article consisting of various cpus would be really useful.
  • tacoslave
    gtx 480 and 460 for reference?
  • Lutfij
    ^ nvidia would loose at this battle. period.
  • spidey81
    I know the FPS/watt wouldn't be as good, but what if the 5670 was crossfired. Would it still be a better alternative, efficiency wise, than say a 5850?
  • nforce4max
    Remember the R600 (2900xt) has a 80nm core while the 5870 has a 45nm core. Shrink the R600 and you will get the 3870 (55nm) that barely uses hardly any.
  • rhino13
    And now just for fun we should compare to Fermi.

    Oh, wait, this just in:
    There is a Fermi comparison chart that was avalible but you needed to have two screens to display the bar graph for Fermi's power consumption and temperature. So the decission was made to provide readers with the single screen only version.
  • aevm
    I loved this part:

    A mere 20 watts separate the Radeon HD 3300, HD 5670, HD 5770, and HD 5870 1 GB. So, in certain cases, the Radeon HD 5870 1 GB can still save enough power to close in on its more mainstream derivatives. Again, this is the case because the cards use a fixed-function video engine to assist in decoding acceleration, which is the same from one board to the next. Thus, even a high-end card behaves like a lower-end product in such a workload. This is very important, as you will see later on.

    My next PC will be used mostly for movie DVDs and Diablo 3. Apparently if I get a 5870 1GB I get the best of both worlds - speed in Diablo and low power consumption when playing movies.

    How about nVidia cards, would I get the same behavior with a GTX 480 for example?
  • Onus
    For those not needing the absolute maximum eye candy at high resolutions in their games, the HD5670 looks like a very nice choice for a do-it-all card that won't break the budget.
    Next questions: First, where does the HD5750 fall in this? Second, if you do the same kinds of manual tweaking for power saving that you did in your Cool-n-Quiet analysis, how will that change the results? And finally, if you run a F@H client, what does that do to "idle" scores, when the GPU is actually quite busy processing a work unit?
  • eodeo
    Very interesting article indeed.

    I'd love to see nvidia cards and beefier CPUs used as well. Normal non green hdds too. Just how big of a difference in speed/power do they make?

    Thank you for sharing.
  • arnawa_widagda
    Hi guys,

    Thanks for reading the article.

    Next questions: First, where does the HD5750 fall in this? Second, if you do the same kinds of manual tweaking for power saving that you did in your Cool-n-Quiet analysis, how will that change the results? And finally, if you run a F@H client, what does that do to "idle" scores, when the GPU is actually quite busy processing a work unit?

    Have no 5750 sample yet, but they should relatively be close to 5770. For this article, we simply chose the best bin for each series (Redwood, Juniper and Cypress).

    The second question, what will happen when you tweak the chip? Glad you ask!! I can't say much yet, but you'll be surprised what the 5870 1 GB can do.

    As for NVIDIA cards, I'm hoping to have the chance to test GF100 and derivatives very soon.

    Take care.
  • JohnnyLucky
    Thanks for including mainstream applications.

    Interesting comments about Furmark.
  • xbsoft
    >> TEST SYSTEM: AMD Phenom II X4 955 Black Edition (3.2 GHz, >>>>>> 8
  • mattmock
    It just means you typically will never encounter such an extreme usage scenario.

    I have to disagree, there are several ways a user can fully load their graphics card in normal use. I have found that my GPU utilization and fan speed go to %100 when I play the dice mini-game in The Witcher. The game only has to render a small game board and the frame rate goes into the 200-300 range. Some thing similar occurs when I hit the pause key in stalker.
  • Fokissed
    xbsoft(3.2 GHz, >>>>>> 8

    bad penis joke?
  • MartenKL
    FPS/watt uses average FPS during the test but max wattage? I am very disappointed by this flawed logic from toms hardware. Spending an entire page describing why everyone else uses flawed testing for benchmarking power efficiency and then doing this simple error is just embarrassing.
  • MartenKL
    I forgot to say I am very interested in this kind of benchmarks and I am glad Toms Hardware is writing a big piece on it, sorry for the harsh words. For me total Wh per completed task for the entire system is the most interesting number. To me that is the only way to measure efficiency. add to that idle power draw and every user can calculate their own usage (by adding tasks and idle hours). Sorry and thanks yet again for an article with a very important topic. My interest is noise and mechanical wear rather than power cost and environment.
  • tubers
    Fermi comparison please :)
  • mayne92
    What a great article by Tom's (Arnawa)! Probably one of the best articles I have read in a long time! Enjoyed the article because was very detailed and you explained everything so well and I LOVE my tech reviews! A Fermi comparison would have been nice but I know that you said that you don't have them to play with so it's said as a request. Hats off to you Arnawa...for a great read...
  • eddieroolz
    Really paints in perspective the power of GPUs compared to CPUs. I really wish that one day we'll be able to use the GPU for central processing.
  • EDIGX2
    Hello everyone
    Well i think this article inspired form the movie that AMD has release lately.
    That movie called as i think "Mis understanding"here's the link:
    As we all know AMD is innovative in power consumption as well It's Graphics I read such this review in ...Just WOW....Loads Of Noise and power flowed for Fermi VGAs . In this review we see the smooth performance for 5670 and 5770.
    and another thing that we should give a hint on is You know releasing Fermi after six month of releasing 5000 series...I think it's good in performance but not after 6 Months!!! but awful in power consuming and noise and heat!!
    Take care guys