MultiGPU Update: Does 3-way Make Sense?
by Derek Wilson on February 25, 2009 2:45 PM EST- Posted in
- GPUs
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.
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Snarks - Wednesday, February 25, 2009 - link
hmm, i find my self questioning these articles more and more..but anyway carry on.
DerekWilson - Wednesday, February 25, 2009 - link
what's the question ... seriously, any criticism is helpful. this is the first time we've really done a series like this, and it's a complicated situation with lots of data and lots of analysis ... there's no one way to look at it, and all the feedback i get will help me down the road.i don't see the need for this type of article or series very frequently, but we'll have to do it every once in a while just in case something changes. knowing what you guys think is important and what you guys want to read about is key to us getting things done right.
Flyboy27 - Wednesday, February 25, 2009 - link
Sell you an extra card that you don't really need.Flyboy27 - Wednesday, February 25, 2009 - link
oh yeah... and a more expensive motherboard, power supply, and case.Burrich - Wednesday, February 25, 2009 - link
Would the recently release Catalyst 9.2 drivers improve any compatibility or fps issues? Their release date was 2/20.7Enigma - Thursday, February 26, 2009 - link
Check out xbitlabs' review of the 9.2 drivers. If you have a 4870 X2 then yes it appears to be a nice upgrade for several games with minimal losses in the games it doesn't benefit. But if you are sporting a single 4870 1gig it actually degrades performance more than it improves!On the flipside they claim stability is better with the 9.2's so it depends on what you want/need. If you are comfortable with the framerates in the games you currently play then jump on the 9.2's for stability reasons. If you are on the edge of playable performance I would stick with the previous drivers...
http://www.xbitlabs.com/articles/video/display/cat...">http://www.xbitlabs.com/articles/video/display/cat...
DerekWilson - Thursday, February 26, 2009 - link
That article compares 9.2 to 9.1 ... the 8.12 hotfix would show similar performance improvements over the 9.1 drivers. 9.2 does benefit more games, but these are games that have been more recently released than the ones we tested.if they compared the 8.12 hotfix to 9.2, we would expect to see more parity, especially with the games we tested in this article.
DerekWilson - Wednesday, February 25, 2009 - link
The recently released 9.2 catalyst drivers are basically the 8.12 hotfix drivers with some additions to support performance and scaling in recently released titles. So not really.smartalco - Wednesday, February 25, 2009 - link
I don't like that you use 0 for those that score under 25 FPS, specifically because that is under 25 at the res/settings you use. If a card scores 24 FPS at 1680*1050 with maxed settings, what that really tells you is that if you were to drop to half the AA, or turn down some other setting, is that you could still have a perfectly playable game. It seems to me, that giving them a value rating of 0 is acting like everyone has to play on max settings, and if it doesn't meet the standard, its useless.IDK, just me talking, I'm going to be happy with my 4850 for quite some time.
Still an excellent article.
DerekWilson - Wednesday, February 25, 2009 - link
i've actually got the graphs without the 0 scores in the article front to back -- just commented out at the moment ... i wasn't sure which one to go with until the last minute, and i thought about putting both in (but that wouldbe really redundant for games that no card had trouble with)i could do some more complex web programming, but i'm not a web developer and i hate javascript ...
thanks for the feedback. i'll be taking it into account in the final article on 4-way.
also, if you wanna see the value numbers for the single and dual cards that scored less than 25 fps, you can still look at the first article and see them.