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Performance Per Watt: The Index

GeForce GTX 680 2 GB Review: Kepler Sends Tahiti On Vacation
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Both AMD and Nvidia claim to be offering unprecedented performance per watt of power consumed, and we believe that both companies are telling the truth.

Nvidia is taking the extra step, though, of adjusting its clock rate and voltage in real-time, based on the premise that no two workloads exact the same power demands. As a result, we can’t simply test one game, divide its average frame rate by average power use, and expect you to believe the outcome is representative of all games. But we also don’t have time to test every game at every resolution (yes, power consumption changes based on resolution, detail settings, and so on). So, we took the games from our suite, set them all to 1920x1080 using the most demanding settings possible, and charted the power behavior for each on all six cards.

This starts a little messy, but it gets easier as we go, so bear with us. First, four different graphics cards in six games. We have the data for GeForce GTX 590 and Radeon HD 6990 as well, but those two cards are just ugly...

It doesn’t matter that some of these tests wrap up before the others. What’s important is that we have the power captured, along with the performance generated during the test run. Charting everything out on a line graph simply shows you the upper and lower bounds for system power use in each game—and that no two games are identical.

Averaging all of the games together, we come up with an average power use figure for each card. AMD’s Radeon HD 7950 uses the least power, on average, followed by Nvidia’s GeForce GTX 680.

We already know that the Radeon HD 7970 is a faster graphics card than Nvidia’s GeForce GTX 580. The fact that it also uses less power tells us it’s more efficient without needing this next graph.

Averaging the frame rates for all six games in our 1920x1080 runs gives us an index of sorts there too, represented in frames per second. The GeForce GTX 680 easily captures the top position, followed by AMD’s Radeon HD 7970. The GeForce GTX 580 takes third place, followed closely by the Radeon HD 7950.

Update (3/23/2012): The original chart on this page showed GeForce GTX 680 at 172% of GeForce GTX 580's performance per watt. This result was derived from an Excel division error, which was noticed by German reader csc. It has since been corrected, yielding a more modest number. The overall effect remains the same, though we're certainly a lot further from Nvidia's original claim of a 2x improvement over GeForce GTX 580. Our apologies for the mistake.

Now, the GeForce GTX 580 is our frame of reference. We want to know how AMD’s and Nvidia’s respective architectures perform in comparison. We set the GTX 580 as 100%, and the rest of the results speak for themselves.

The Radeon HD 7970 and 7950 both do deliver more performance per watt of power used compared to GeForce GTX 580—and by a significant amount. But GeForce GTX 680 is like, way up there.

As a gamer, do you care about this? Not nearly as much as absolute performance, we imagine. And I personally doubt I’d ever pay more for a card specifically because it gave me better performance/watt. But with AMD and Nvidia both talking about their efficiency this generation, thanks to 28 nm manufacturing and new architectural decisions, the exercise is still interesting.

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Top Comments
  • 44 Hide
    borden5 , March 22, 2012 12:55 PM
    oh man this's good news for consumer, hope to see a price war soon
  • 38 Hide
    Anonymous , March 22, 2012 12:46 PM
    Hail to the new king.
  • 33 Hide
    outlw6669 , March 22, 2012 12:59 PM
    Nice results, this is how the transition to 28nm should be.
    Now we just need prices to start dropping, although significant drops will probably not come until the GK110 is released :/ 
Other Comments
  • 38 Hide
    Anonymous , March 22, 2012 12:46 PM
    Hail to the new king.
  • 44 Hide
    borden5 , March 22, 2012 12:55 PM
    oh man this's good news for consumer, hope to see a price war soon
  • 26 Hide
    johnners2981 , March 22, 2012 12:58 PM
    Damn prices, in europe we have to pay the equivalent of $650-$700 to get one
  • 33 Hide
    outlw6669 , March 22, 2012 12:59 PM
    Nice results, this is how the transition to 28nm should be.
    Now we just need prices to start dropping, although significant drops will probably not come until the GK110 is released :/ 
  • 23 Hide
    Anonymous , March 22, 2012 1:00 PM
    Finally we will see prices going down (either way :-) )
  • -4 Hide
    Scotty99 , March 22, 2012 1:03 PM
    Its a midrange card, anyone who disagrees is plain wrong. Thats not to say its a bad card, what happened here is nvidia is so far ahead of AMD in tech that the mid range card purposed to fill the 560ti in the lineup actually competed with AMD's flagship. If you dont believe me that is fine, you will see in a couple months when the actual flagship comes out, the ones with the 384 bit interface.
  • 26 Hide
    Chainzsaw , March 22, 2012 1:04 PM
    Wow not too bad. Looks like the 680 is actually cheaper than the 7970 right now, about 50$, and generally beats the 7970, but obviously not at everything.

    Good going Nvidia...
  • 32 Hide
    SkyWalker1726 , March 22, 2012 1:05 PM
    AMD will certainly Drop the price of the 7xxx series
  • 20 Hide
    rantoc , March 22, 2012 1:13 PM
    2x of thoose ordered and will be delivered tomorrow, will be a nice geeky weekend for sure =)
  • 23 Hide
    Scotty99 , March 22, 2012 1:21 PM
    scrumworksNothing surprising here. Little overclocking can put Tahiti right at the same level. Kepler is actually losing to Tahiti in really demanding games like Metro 2033 that uses the latest tech. Pointless to test ancient and low tech games like World of Warcrap that is ancient, uses dx9 and is not considered cutting edge in any meter.


    Sigh...

    WoW has had DX11 for quite a long time now. Also, go play in a 25 man raid with every detail setting on ultra with 8xAA and 16x AAF and tell me WoW is not taxing on a PC.
  • 16 Hide
    yougotjaked , March 22, 2012 1:21 PM
    Wait what does it mean by "if you’re interested in compute potential, you’ll have to keep waiting"?
  • 0 Hide
    dragonsqrrl , March 22, 2012 1:22 PM
    Just throwing this out there now, but some AMD fanboy will find a way to discredit or marginalize these results.

    ...oh, wait.
  • 24 Hide
    klausey , March 22, 2012 1:24 PM
    Great to see nVidia jumping back into the game and forcing AMD to lower its prices accordingly. I was shocked to see the card actually available at the MSRP of $500 on launch day. I guess we'll see how long that lasts.

    For everyone suggesting that nVidia will release another true "flagship" beyond the 680, I think you are spot on, IF AMD gives them a reason to. There's no reason to push it at the moment as they already hold the crown. If, on the other hand, AMD goes out and makes a 7980, or 79070 SE card with higher clocks (more like what the 7970 can achieve when properly overclocked), I definitely see nVidia stepping their game up a bit.

    Either way, it's awesome to see both AMD and now nVidia taking power consumption into consideration. I'm tired of my computer room feeling like a toaster after an all nighter.
  • 18 Hide
    rantoc , March 22, 2012 1:24 PM
    yougotjakedWait what does it mean by "if you’re interested in compute potential, you’ll have to keep waiting"?


    He means waiting for the GK110, that will be a more of a compute card while this GK104 is more equiped towards gaming.
  • 13 Hide
    EXT64 , March 22, 2012 1:26 PM
    Really disappointing DP compute, but a tradeoff had to be made and this card is meant for gaming, so I can understand their position. Hopefully GK110 is a real card and will eventually come out.
  • -7 Hide
    Anonymous , March 22, 2012 1:27 PM
    but will it run tetris with multiple displays?
  • 7 Hide
    amk-aka-Phantom , March 22, 2012 1:27 PM
    Oh yeah, team green strikes back! :D  Now let's see what 660 Ti will be like, might suggest that to a friend.
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