Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI

Features
By Thomas Soderstrom
published

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.

Multi-GPU Scaling Analysis

So, are two cards twice as powerful as one? Are three cards 50% better than two? We compared each two-way and three-way configuration to its own single-card scores to find out, and split the charts to remind readers that the GeForce GTX 570 SLI scaling analysis uses a GeForce GTX 570 baseline, while the Radeon HD 6950 CrossFire analysis uses a Radeon HD 6950 baseline.

Two HD 6950s are up to 78% better than one at 1680x1050, beating Nvidia’s 58% gain by a wide margin. A third GPU is nearly wasted by either technology at this setting, as we'd expect.

It takes three GeForce GTX 570s to match the scaling of two HD 6950s at 1920x1080. On the other hand, our previous page showed that Nvidia’s higher baseline made two-way configurations the only “proper” performance match.

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 145% 3-way gains put it in the winner’s circle.

This, in spite of the fact that one of our games, Aliens vs. Predator, didn’t even benefit from the third AMD card.

Thomas Soderstrom
Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.
163 Comments Comment from the forums
  • amk09
    :( i wish i could afford that
    Reply
  • tacoslave
    wow even though a 6950 is weaker than a 570 it dominates at higher resolutions eyefinity here i come.
    Reply
  • scrumworks
    Impressive and unexpected results. Speculations that crossfire scaling is worse than SLI can finally be put into rest.
    Reply
  • aznguy0028
    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.
    Reply
  • aznguy0028
    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 :)
    Reply
  • liquidsnake718
    Now im thinking if i should even spend on a now older 5850 to crossfire on my X58.
    Reply
  • bavman
    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.
    Reply
  • _Pez_
    I would get two HD 6870 for a mobile crossfirex gaming rig ! :D
    Reply
  • anubis44
    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.
    Reply
  • Maziar
    Great review ! It's good to see AMD did a lot of work on CF scaling.
    Reply