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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Hauk - Monday, February 23, 2009 - link
To you grammer police... get a life will ya?!?Who gives a rats ass! It's the data!
Your smug comments are of ZERO value here. You want to critique, go to a scholarly forum and do so.
Your whining is more of a distraction! How's that for gramaticly correct?
Slappi - Tuesday, February 24, 2009 - link
It should be grammar not grammer.
SiliconDoc - Wednesday, March 18, 2009 - link
Grammatically was also spelled incorrectly.lol
The0ne - Monday, February 23, 2009 - link
"In general, more than one GPU isn't that necessary for 1920x1200 with the highest quality settings,..."I see many computer setups with 22" LCDs and lower that have high end graphic cards. It just doesn't make sense to have a high end card when you're not utilizing the whole potential. Might as well save some money up front and if you do need more power, for higher resolutions later, you can always purchase an upgrade at a lower cost. Heck, most of the time there will be new models out :)
Then again, I have a qaud-core CPU that I don't utilize too but... :D
7Enigma - Monday, February 23, 2009 - link
Everyone's situation is unique. In my case I just built a nice C2D system (OC'd to 3.8GHz with a lot of breathing room up top). I have a 4870 512meg that is definitely overkill with my massive 19" LCD (1280X1024). But within the year I plan on giving my dad or wife my 19" and going to a 22-24". Using your logic I should have purchased a 4850 (or even 4830) since I don't NEED the power. But I did plan ahead to future proof my system for when I can benefit from the 4870.I think many people also don't upgrade their systems near as frequently as some of the enthusiasts do. So we spend a bit more than we would need to at that particular time to futureproof a year or two ahead.
Different strokes and all that...
strikeback03 - Monday, February 23, 2009 - link
The other side of the coin is that most likely for similar money, you could have bought something now that more closely matches your needs, and a 4870 in a year once it has been replaced by a new card if it still meets your needs.7Enigma - Tuesday, February 24, 2009 - link
Of course. Or I could spend $60 now, another $60 in 3 months, and you see the point. It's all dependant on your actual need, your perceived need, and your desire to not have to upgrade frequently.I think the 4870 is one of those cards like the ATI 9800pro that has a perfect combination of price and performance to be a very good performer for the long haul (similarly to how the 8800GTS was probably the best part from a price/performance/longevity standpoint if you were to buy it the day it first came out).
Also important is looking at both companies and seeing what they are releasing in the next 3-6 months for your/my particular price range. Everything coming out seems to be focused either on the super high end, or the low end. I don't see any significant mid-range pieces coming out in the next 3-6 months that would have made me regret my purchase. If it was late summer or fall and I knew the next round of cards were coming out I *may* have opted for a 9600GT or other lower-midrange card to hold over until the next big thing but as it stands I'll get easily a year out of my card before I even feel the need to upgrade.
Frankly the difference between 70fps and 100fps at the resolutions I would be playing (my upgrade would be either to a 22 or 24") is pretty moot.
armandbr - Monday, February 23, 2009 - link
http://www.xbitlabs.com/articles/video/display/rad...">http://www.xbitlabs.com/articles/video/display/rad...here you go
Denithor - Monday, February 23, 2009 - link
Second paragraph, closing comments:Fourth paragraph, closing comments:
Please remove the apostrophe from the first sentence (where it should read its) and instead move it to the second (which should be we're).
Otherwise excellent article. This is the kind of work I remember from years past that originally brought me to the site.
One thing - would it be too difficult to create a performance/watt chart based on a composite performance score for each single/pair of cards?
I do think you really pushed the 4850X2 a bit too much. The 9800GTX+ provides about the same level of performance (better in some cases, worse in others) and the SLI version manages to kick the crap out of the GTX 280/285 nearly across the board (with the exception of a couple of 2560x1600 memory-constricted cases) at a lower price point. That's actually in my mind one of the best performance values available today.
SiliconDoc - Wednesday, March 18, 2009 - link
Forget about Derek removing the apostrophe, how about removing the raging red fanboy ati drooling ?When the GTX260 SLI scores the 20 games runs of 21, and the 4850 DOESN'T, Derek is sure to mention not the GTX260, and on the very same page blab the 4850 sapphire "ran every test"...
This is just another red raging fanboy blab - so screw the apostrophe !
Nvidiai DISSED 'em because they can see the articles Derek posts here bleeding red all over the place.
DUH.