Earlier this week we posted the first article in a series of articles on multiGPU performance, scaling and value. The first article focused on two GPU configurations in both single card and dual card flavors. This is the next installment and today we will cover 3-way performance, scaling and value in much the same way as our first article.

The way we will look at scaling and value are mostly unchanged, with a slight exception in the value department. While we will still be ranking solutions by FPS / $100US (how much performance do you get for every 100 USD spent), we are also taking into account another value factor. As was suggested in our comments on the original article, we are zeroing out the value of solutions that don't provide playable framerates. We give ourselves a wide birth and put the cutoff at 25 fps as some people do get by with lower framerates. For instances where a configuration comes in at less than 25 fps, we assign a value of zero. Changing the way we look at value should help us get a better picture of how both absolute performance and performance per dollar play into the value of a given setup.

While scaling is calculated the same, we are looking at two different metrics. Rather than look again at 1 to 2 GPU scaling, we are looking at peformance scaling from 1 to 3 GPUs and from 2 to 3 GPUs. There will be one more set of bar graphs on every page this time, but we hope to give a well rounded picture of the performance improvement with three cards. Unlike the move from 1 to 2 cards, we aren't looking at a theoretical max of 2x performance in non-CPU limited situations. With the increase from 1 to 3 cards, we could see as much as 200% performance improvement (3x the performance) in theory. We don't get anywhere near this in practice though.

Moving from 2 to 3 cards, the maximum performance improvement we would expect to see with perfect scaling and no CPU or system limitation is 50%. While we might see good scaling from 1 to 3 cards, moving from 2 to 3 cards might show a much less significant improvement. Looking at both metrics will help us get a feel for scaling in general and scaling/value of 3-way as compared to 2-way multiGPU solutions.

For color coding, we find that more than 4 colors in a bar graph can get distracting, so we tried to strike a balance in color use and readability by coloring all the configurations we already looked at in the first installment blue. 3-way AMD solutions are orange and 3-way NVIDIA solutions are green. Representing this much data in a clear fashion is always a balance. Hopefully this does a good job of getting things across.

As with last time, we'll look at how often games scale with 3 cards. This will be based on scaling from one to three as well as from two to three, and we will see more diminishing returns on 3 cards than on two. This is to be expected, but theoretically those who spring for three cards are not interested in thrift anyway. Our value graphs will tie together the performance scaling and price data. What we expect to see is that, even more than 2-way solutions, 3-way multiGPU options require a much higher premium for the performance they deliver and are only really viable options for owners of 2560x1600 monitors.

Who Scales
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  • MagicPants - Wednesday, February 25, 2009 - link

    I've been playing a bit of GTA4 recently, it runs well on my dual 285 system but I've heard there is no SLI support. It might be nice to include a few of these types of games in the mix.

    Honestly the only game I've played where SLI matters (on 1920x1200) is Crysis.
    Reply
  • MagicPants - Wednesday, February 25, 2009 - link

    Having the cutoff of 25fps really effected the value of cards. It was interesting to see the values at different resolutions as well.

    Now I just want to see an interactive graph where I can enter a game and a resolution and it will tell me what video card is the best value. That's not asking too much is it? :)

    ... or enter a game and resolution and the thing tells me what to put in my system (cpu, memory, motherboard, video card)
    Reply
  • plonk420 - Wednesday, February 25, 2009 - link

    i'm not even a proponent of SLI/dualGPU until 100% of games work with the technology (and see a worthwhile increase of performance). Reply
  • mastrdrver - Wednesday, February 25, 2009 - link

    I think it would have been interesting to see a 2 and 3 way of the 4830 added to all this. Sure it maybe on the lowend of things, but it could have a great value at maybe 1920 and 1680 compared to the more expensive counterparts. Reply
  • stym - Thursday, February 26, 2009 - link

    I would like to see that too. I am going to buy a new system next month and I am torn between a single 4870 and two 4830. Same price tag, but what about performance? The problem is, it should have been considered in the previous article. Although I am convinced a two-way 4830 crossfire configuration may provide great performance at a budget price, I doubt a 3-way 4830 makes a lot of sense in a system. You would have to buy a MoBo with three x16 PCI Express slots, and I would not pair that with lower end cards. Reply
  • mastrdrver - Friday, February 27, 2009 - link

    It could be a cheap way to go to an i7 platform with power. Spend all the money on the board/memory/cpu and spend ~$300 USD on 3 cards that have a lot of power. If the 4380s scales as well as either the 4850 or 4870, you could have a very powerful but cheap card setup. Not even 300 will buy you a 4870x2. Sure 3 4830s won't beat it, but it will be between a 4870 and the x2. For $300, it sounds like a great deal. Reply
  • Razorbladehaze - Wednesday, February 25, 2009 - link

    "Pairing a single card dual GPU AMD card with a single card single GPU option to get 3-way CrossFireX also seems to have a positive impact on microstutter. "

    I am a little unclear by this statement, I read it as, pairing this combo eliminates the microstutter. But i am concerned that a positive impact could also mean that the FPS in spite of microstutter increases.

    This really was the article of most interest to me, as opposed to the 2-way, or 4-way configurations. I find the graphs to be clear and concise with the information they convey.

    I find it surprising that there is less discussion on image quality or distortions during benches (yes i know it is difficult to qualitative judge this). I find it hard to believe that these configurations run these game without much flaws, glitches, tearing, flickering in image quality, as my experience has been. I suppose though that if all these issues are resulting from driver optimizations as i suspect, then these commonly benchmarked, newer games get those driver tweaks.

    Anyways the only real comments that may be helpful to the actual presentation of material is i agree with the other fellow that the zero point is not contiguous within the graphs. The more accurate the information the better, as opposed to creating a null value, most people understand what is "playable" for their tastes in different genres (at least most people that i believe read these sites). Further I know that my next suggestion is not as mathematically clean as what you have done, but would produce more useful (based upon card prices/selling points) results. Instead of the FPS per $100 spent, change to FPS per $20 or $50 ($50 would be my choice).

    Reply
  • Antman56 - Wednesday, February 25, 2009 - link

    I wrote an article about it weeks ago. Its a 4850X2 2GB crossfired with a 4850 1GB. Its good.

    http://forums.anandtech.com/messageview.aspx?catid...">http://forums.anandtech.com/messageview.aspx?catid...
    Reply
  • Denithor - Wednesday, February 25, 2009 - link

    to the third card option - when the addition of that extra card results in decreased performance? Shouldn't those ones get "0" value ratings? Reply
  • DerekWilson - Wednesday, February 25, 2009 - link

    good point ... we'll try and refine it a little more. Reply

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