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Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI

Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI
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Two GPUs are great, but are three that much better? When it comes to multi-card scaling, can AMD finally beat Nvidia? Who really needs this much performance? We loaded a super-fast system in single-, dual-, and triple-GPU configurations to find out.

Tom's Hardware's Three-Part, 3-Way Graphics Scaling Series

Part 1, The Cards: Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI
Part 2, The Slots: GeForce And Radeon On Intel's P67: PCIe Scaling Explored
Part 3, The Chipsets: P67, X58, And NF200: The Best For CrossFire And SLI

The battle for GPU supremacy is a bit of a waiting game. The recent launch of AMD's Radeon HD 6990 (AMD Radeon HD 6990 4 GB Review: Antilles Makes [Too Much] Noise) and upcoming introduction of Nvidia's GeForce GTX 590 help demonstrate.

Roughly every six moths, two companies with similarly-capable products wait to see what the other one will showcase, hoping to trump that introduction a few days later by tweaking the clocks, power, and configuration of their own product. Both firms use these delays to build anticipation among followers. Though, as that very same 6990 story showed us, being a "fan" of either company is just silly. Why make excuses for one design team's poor execution and then slam the competition for the very same thing? 

Yet, in spite of the hysteria, the past few GPU launches have barely budged the performance bar. For those who prefer to play at high resolutions without giving up any of a modern game’s splendor, multi-GPU configurations (and that includes the latest and upcoming dual-GPU cards) are still mandatory.

Launch articles rarely include multi-GPU tests, partly because most reviewers have only one card. The few reviewers that do get multiple cards often find SLI and CrossFire bugs persisting until two or three software revisions after a new card is launched, leading to hopeful comments from loyal enthusiasts like, "just wait until they get their driver situation worked out!"

As a result, when we as reviewers get asked about multi-GPU scaling, it's often really hard to answer definitively. The real data has to be collected once availability is more stable, and after driver problems have been more thoroughly addressed. 

It's Time To Explore Multi-Card Scaling

Today’s question isn’t which single-GPU card is best, but which cards operate best in pairs and trios. Though current buyers can now save even more money with the 1 GB version, AMD's Radeon HD 6950 2 GB was its least expensive three-way CrossFire option when we set up this article.

The closest competitor is Nvidia’s GeForce GTX 570 1280 MB, a model that also represents its cheapest-current three-way SLI configuration. Anything less and you only get a single SLI link, support two-way setups.

We've already seen fantastic scaling from three-way SLI, so perhaps the biggest question is whether AMD’s scaling had really improved to the point where it can yank the trophy out of its rival’s hands. We've seen two-way numbers that suggest yes, in fact, Radeons work much better together now than in the past.

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Top Comments
  • 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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