MultiGPU Update: Two-GPU Options in Depth
by Derek Wilson on February 23, 2009 7:30 AM EST- Posted in
- GPUs
Who Scales: How Often?
A major topic in the multiGPU arena is software support. And there are two large factors here: how many titles benefit and how much do those titles benefit. In the past we've seen SLI provide scaling more frequently and consistently than CrossFire (especially right when games come out). With CrossFire we'll often see support for older games get broken in newer drivers and then fixed when a review site happens to stumble upon the issue. But we've also noted that when CrossFire worked, it worked really well. It's honestly been a long time since we did a quantitative analysis of how SLI and CrossFire really stack up as technologies, and there's no time like the present.
First we will explore whether performance scaling happened in our suite of games. We've looked at two different metrics to judge our cards, both of which look at percent increase from 2 GPUs. If we consider the success of a multiGPU solution to be contingent on a performance improvement of at least 30% out of a possible 100%, we can count the number of times we see success in our benchmarks as a benchmark. We ran 21 different tests (7 games at 3 different resolutions), so keep that in mind when looking at this of list successes per configuration.
| NVIDIA GeForce GTX 285 | 17 |
| NVIDIA GeForce GTX 280 | 18 |
| NVIDIA GeForce GTX 260 | 20 |
| NVIDIA GeForce 9800 GTX+ | 19 |
| ATI Radeon HD 4870 512MB | 17 |
| ATI Radeon HD 4850 | 19 |
| ATI Radeon HD 4870 1GB | 16 |
Since this takes into account CPU limited cases, our higher performance SLI and CrossFire solutions will see cases where 1680x1050 or even 1920x1200 isn't a high enough resolution to allow for any real improvement. Cards that look good by this metric are ones that both scale well and start off at a low enough performance point so as to allow good scaling to happen even at lower resolutions (well, lower for multiGPU application anyway). This shows the GTX 260 and the 4850 hit a sweet spot in terms of scaling and baseline performance in modern games to provide benefit for a larger number of users (many more people have 1680x1050 and 1920x1200 than 2560x1600 monitors). Because this 9800 GTX+ is older, we see headroom here too.
If we exclude the simply CPU limited cases and look at cases where the multiGPU solution got near zero or negative performance improvement we see a slightly different picture. Our data is on a per game basis, so all of these numbers are out of 7.
| NVIDIA GeForce GTX 285 | 7 |
| NVIDIA GeForce GTX 280 | 7 |
| NVIDIA GeForce GTX 260 | 7 |
| NVIDIA GeForce 9800 GTX+ | 6 |
| ATI Radeon HD 4870 512MB | 6 |
| ATI Radeon HD 4850 | 5 |
| ATI Radeon HD 4870 1GB | 7 |
This shows cases where certain multiGPU configurations have zero value to help improve performance because of some failing of the graphics solution. All these cases happen to be issues at 2560x1600 where the resolution proved too much to handle because of the limited amount of onboard RAM.
It's also important to point out that the Sapphire 4850 X2 doesn't suffer from the problems of the 4850 CrossFire we show here. The Sapphire card scales and performs well in every test we ran.
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makdaddy626 - Monday, February 23, 2009 - link
I really appreciate the article and all the research and work that went into it. Kudos to you for it.A small suggestion would be to take into account a minimal playable frame rate in the value and performance per dollar data, where a ZERO would be substituted for the frame rate in instances where a card failed to reach a playable rate for a given game/resolution. I feel this would more accurately reflect the value of the card(s) as 15 FPS in most games presents no value.
Mastakilla - Monday, February 23, 2009 - link
I agreeMinimum framerates should be more important then average ones even...
Interesting article though! I didn't know the 4850x2 was so competitive...
Only in Crysis it does worse the the 285, which I had in mind for my new pc...
That does make me wonder if the 285 might be a more future proof investment...
makdaddy626 - Monday, February 23, 2009 - link
Yes, But I meant "minimum" in the sense of what the game needs to be played at, even you measure "average" - I just don't think it's fair to say that the 9800 GTX shows the highest performance per dollar on the Crysis Warhead 2560x1600 chart when it turns in frame rates of 13.5. To me that is ZERO value for the money because it's not playable. Someone wanting to play at those settings would be wasting EVERY dollar spent on the 9800 GTX.7Enigma - Tuesday, February 24, 2009 - link
Completely agree. Statistics mean nothing when not taken in a proper context. Zero, NA, or just leaving it blank would be much better. Someone looking to use that card would then click on a lower resolution and see if it is a viable choice. It would reduce the amount of data that needed to be compared as the reader of the article, and make caveats like in the explaination section about comparing between cards/resolutions etc. almost moot.Spivonious - Monday, February 23, 2009 - link
The framerate charts are all but worthless if you're focusing on how performance scales. Why not some line graphs with all three resolutions shown and card models along the x-axis? Then the reader could see how performance is affected by the lower memory of some models and how it scales linearly with the higher-end cards.7Enigma - Monday, February 23, 2009 - link
I would have to agree with this. I always enjoyed the broken line graphs that show multiple resolutions and framerates in the same graph. It makes comparisons very easy and more importantly allows EVERYONE to see their particular resolution without having to click on a link for a separate graph.It's fine to keep your specialized performance/$ and % increase from a single card the way you have it as I understand what you mean about not comparing between resolutions but for the general frame rate comparisons I preferred the old way.
One thing I failed to see which I have seen in previous reviews with X-fire/SLI (or was it with tri/quad setups?) is the stuttering that can be present. I thought it was an Anand article but could have been from another site.
SiliconDoc - Wednesday, March 18, 2009 - link
The charts are designed to autopop to 2650x - and we all know the red ragers have screamed the ati cards are great there.EVERY CHART pops to the favored ati $2,000.00 monitor resolution.
It's not an accident, Derek made them.
C'DaleRider - Monday, February 23, 2009 - link
Derek, if you want to impress, and this article does with its research, please invest in some writing manuals and learn some grammar.Take this sentence:
"This unique card really shined and held it's own all the way up to 2560x1600."
Your use of "IT'S" in this instance is incorrect. IT'S is a contraction for IT IS, not a possessive word, which is ITS.
Or take this passage, "It's very surprising to us that AMD hasn't pushed this configuration and that Sapphire are the only manufacturer to have put one of these out there."
Sapphire is a company or organization, I realize that. But in this instance, you're referring to a group in its singular fashion, or as a single unit. That context is seen by the only manufacturer in the sentence.
That sentence should have read. "It's very surprising to us that AMD hasn't pushed this configuration and that Sapphire IS the only manufacturer to have put one of these out there."
Here's the rule for that (taken from both MLA and APA handbooks): If the action of the verb is on the group as a whole, treat the noun as a singular noun. If the action of the verb in on members of the group as individuals, treat the noun as a plural noun.
This means companies, such as Microsoft, IBM, Sapphire, Ford, etc., when being referred to the company as a whole collective, single entity, has to have a singular verb.
But, if you are referring to pieces of the whole, such as "the engineers of Ford are.....", or "The programmmers at Microsoft are.....".
Please invest in some proper English grammar texts and take time to read and learn from them. Your error laden grammar you write and use is quite distracting and detracts from what is supposed to be a professionally run hardware site.
Hire a proofreader or good copy editor if learning proper grammar is too difficult.
Otherwise, this was a great article!
The0ne - Monday, February 23, 2009 - link
I don't really mind Anandtech articles as much in terms of presentation, spelling and graphics. Other sites such as Ars Technica, x-bit labs, and so forth are much worst. The first is first since they've started writing articles concerning everything, it seems.If I did mind, I say stick to the general guidelines writing manuals, procedures, pamphlets, technical docs, etc. But being online, this isn't the case and won't ever be. Again, I don't mind as much because I do the same thing myself where I hardly pay attention to spelling or grammar when writing online. It's only when I write short stories or for work that I pay attention. Strange but comfortsure does make one do these things :)
And yes, I do write all sorts of articles daily.
oldscotch - Monday, February 23, 2009 - link
"Your error laden grammar you write and use is quite distracting and detracts from what is supposed to be a professionally run hardware site."That should read "The error laden grammar you use is quite distracting..." or just "Your error laden grammer is quite distracting..."
"Your error laden grammam you write and use..." is redundant.
Perhaps you should learn some grammar yourself before criticizing others about theirs.