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CrossFire Scales Spectacularly

Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI
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While past reviews have shown that big multi-GPU performance gains are usually limited to more mainstream cards, today’s CrossFire results make a far better-than-expected impression.

AMD’s Radeon HD 6950 is anything but low-end, and yet its second card provides a huge 92% lead over a single board. Almost as impressively, a third card delivers an impressive 27% lead over two cards at “only” 2560x1600. We could expect even better results at higher resolutions, if only this lab had the monitors for that test. That’s why I just expensed two more 2560x1600 displays to support additional testing (just kidding, boss)!

Fears of three-way CrossFireX not being supported by a variety of games were almost put to rest when only a single game, Aliens vs. Predator, didn't realize any scaling improvements when we added a third card. While we still have minor concerns about what other games might suffer similarly (after all, AMD couldn't get F1 2010 working with anti-aliasing until zero-hour for our Radeon HD 6990 review), no performance gain in only one of five tested titles gives us a great deal of confidence in the company's compatibility efforts moving forward. Aliens vs. Predator is the one game where SLI showed its best scaling, a fact that we find odd given that this is not a “TWIMTBP” title.

CrossFire came out with a huge overall scaling lead over SLI, and removing the one title that didn’t reflect that average would have made the lead even bigger. Superior scaling allowed two mid-priced Radeon HD 6950s to approximate the performance of two higher-cost GeForce GTX 570s, while three HD 6950s took the performance win over three GTX 570s.

If CrossFire’s value-oriented victory in two-way and performance win in three-way configurations weren’t enough to convince us, the Radeon HD 6950's lower power certainly did. AMD started out with the highest efficiency at one card, and superb multi-GPU scaling allowed its efficiency to increase with every card we added. When’s the last time adding parts made your machine more efficient?

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  • 15 Hide
    scrumworks , March 14, 2011 5:23 AM
    Impressive and unexpected results. Speculations that crossfire scaling is worse than SLI can finally be put into rest.
Other Comments
  • 4 Hide
    amk09 , March 14, 2011 5:11 AM
    :(  i wish i could afford that
  • 8 Hide
    tacoslave , March 14, 2011 5:12 AM
    wow even though a 6950 is weaker than a 570 it dominates at higher resolutions eyefinity here i come.
  • 15 Hide
    scrumworks , March 14, 2011 5:23 AM
    Impressive and unexpected results. Speculations that crossfire scaling is worse than SLI can finally be put into rest.
  • -2 Hide
    aznguy0028 , March 14, 2011 5:33 AM
    scrumworksImpressive and unexpected results. Speculations that crossfire scaling is worse than SLI can finally be put into rest.

    Not true, I would have liked to see more games on the test. The choices were too limited for my taste. For example, everyone knows that Crysis is heavily Nvidia favored, so it's not surprising to see those results in the least.

    Here's another article on the 68xx series in Xfire
    http://www.xbitlabs.com/articles/video/display/radeon-hd6870-hd6850-crossfirex.html#sect0

    Xfire scaling was found to be 100% on 10 or the 19 games they tested, and remaining very high on the others. Nvidia and ATi seems to trade blows at different games tested, but it is evident that Ati has stepped up their Xfire drivers int he 6xxx series.
  • 7 Hide
    aznguy0028 , March 14, 2011 5:35 AM
    scrumworksImpressive and unexpected results. Speculations that crossfire scaling is worse than SLI can finally be put into rest.

    I misunderstood what you meant. But yes, xfire/sli scaling has improved alot this generation :) 
  • 2 Hide
    liquidsnake718 , March 14, 2011 6:11 AM
    Now im thinking if i should even spend on a now older 5850 to crossfire on my X58.
  • 5 Hide
    bavman , March 14, 2011 6:22 AM
    Its really cool to see amd stepping up their game. Multigpu scaling used to be only good on nvidia, but now amd is beating them. Though i feel that more games should be tested before a firm conclusion should be drawn.
  • 1 Hide
    _Pez_ , March 14, 2011 6:22 AM
    I would get two HD 6870 for a mobile crossfirex gaming rig ! :D 
  • 1 Hide
    anubis44 , March 14, 2011 6:30 AM


    No! Don't buy a 5000-series card to crossfire. The 6000 series cards are essentially all better at crossfire scaling than their predecessors. This performance advantage will likely only increase with additional driver revisions and better 6000-series optimization support than for older products.
  • 2 Hide
    Maziar , March 14, 2011 6:30 AM
    Great review ! It's good to see AMD did a lot of work on CF scaling.
  • 3 Hide
    classicaxe , March 14, 2011 6:31 AM
    I wish you Tom's would have done a 6970 trifire comparison instead. It's on average cheaper than the 570 on the Egg right now. I guess i get the memo, with showing that a cheaper solution is outperforming a more expensive option, but there would have been a good deal of performance increase across the board with the clock speed differences and opened shaders that is the 6970. Those differences come more alive in scaling especially with 3 cards.
  • 1 Hide
    Rizlla , March 14, 2011 6:35 AM
    You can see that AMD knows multicard setups are the future. Now i really want to get my 6950 :) 
  • 0 Hide
    avatar_raq , March 14, 2011 6:40 AM
    @Thomas:
    You can test eyefinity resolutions on single monitor IF that monitor has 3 inputs. Can you give this a try please?
  • 3 Hide
    anubis44 , March 14, 2011 6:52 AM
    Holy crap! After reading this review, I decided to look into the 6950 cards again.

    If you're in Canada, you can get an XFX 6950 1Gb card for $215.99 (after rebate)right now from NCIX! That's a stupidly amazing deal!!! Think I'll grab one!
    http://www.ncix.com/products/index.php?sku=58455&vpn=HD695XZNFC&manufacture=XFX&promoid=1293
  • 3 Hide
    Luay , March 14, 2011 7:21 AM
    Loved the idea of the article. Very disappointed with the display setup. It should go up to 5760x1200.
  • 2 Hide
    Crashman , March 14, 2011 7:27 AM
    LuayLoved the idea of the article. Very disappointed with the display setup. It should go up to 5760x1200.
    Asus' 25" 1920x1200 display is still well priced, but I don't expect to see them around much longer. You should tell Chris to order three of these for every editor, before that bargain price vanishes!
  • 1 Hide
    liquidchild , March 14, 2011 7:28 AM
    why not test the 6970 and the 570? they are the same price point, the 6950 is one tier lower.
  • 0 Hide
    Sihastru , March 14, 2011 7:40 AM
    Quote:
    Things get ugly for Nvidia at 2560x1600. While a 67% performance gain for two-way and 112% gain for three-way SLI certainly aren't shabby, AMD’s 92% two-way and 245% 3-way gains put it in the winner’s circle.
    Well the graph for nVidia shows 212.11%, so a 112% gain is correct, but the graph for AMD shows 244.87%, so 245% gain is incorrect, that should be 145% gain. Still better then nVidia, but not that much better...
  • -6 Hide
    executor2 , March 14, 2011 7:45 AM
    "The closest competitor is Nvidia’s GeForce GTX 570" Wrong !

    The closest competitor is the Nvidia`s GTX 560Ti price vs price. At least in my country.
  • 7 Hide
    Crashman , March 14, 2011 7:50 AM
    executor2"The closest competitor is Nvidia’s GeForce GTX 570" Wrong ! The closest competitor is the Nvidia`s GTX 560Ti price vs price. At least in my country.
    Could you please show me the GTX 560 Ti model that supports 3-way SLI? I'd love to test those too!
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