Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI

J

tom's hardware: Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI : Is Multi-GPU The Game Changer?

tom's hardware said:
CrossFire Scales Spectacularly

While past reviews have shown that big multi-GPU performance gains are usually limited to more mainstream cards, today’s CrossFire results make a far better-than-expected impression.

AMD’s Radeon HD 6950 is anything but low-end, and yet its second card provides a huge 92% lead over a single board. Almost as impressively, a third card delivers an impressive 27% lead over two cards at “only” 2560x1600. We could expect even better results at higher resolutions, if only this lab had the monitors for that test. That’s why I just expensed two more 2560x1600 displays to support additional testing (just kidding, boss)!

Fears of three-way CrossFireX not being supported by a variety of games were almost put to rest when only a single game, Aliens vs. Predator, didn't realize any scaling improvements when we added a third card. While we still have minor concerns about what other games might suffer similarly (after all, AMD couldn't get F1 2010 working with anti-aliasing until zero-hour for our Radeon HD 6990 review), no performance gain in only one of five tested titles gives us a great deal of confidence in the company's compatibility efforts moving forward. Aliens vs. Predator is the one game where SLI showed its best scaling, a fact that we find odd given that this is not a “TWIMTBP” title.

CrossFire came out with a huge overall scaling lead over SLI, and removing the one title that didn’t reflect that average would have made the lead even bigger. Superior scaling allowed two mid-priced Radeon HD 6950s to approximate the performance of two higher-cost GeForce GTX 570s, while three HD 6950s took the performance win over three GTX 570s.

If CrossFire’s value-oriented victory in two-way and performance win in three-way configurations weren’t enough to convince us, the Radeon HD 6950's lower power certainly did. AMD started out with the highest efficiency at one card, and superb multi-GPU scaling allowed its efficiency to increase with every card we added. When’s the last time adding parts made your machine more efficient?

so.. hd 6950 scale better than gtx 570 sli.

AMD has improved drivers, i guess.

also 3rd card from both company is just not worth it.

but i think tom should have waited for 11.4 as they are said to have great performance improvements.

HD 6970 would have made this look worse and why they didn't wait for 11.4?

wow
guess the AMD crossfire issues are more or less over now

BTW when is 11.4 WHQL arriving?

^^
Early BETA is out on guru..!

Downloaded 11.4 and doing some testing. Slight improvement in fps till now.

cilus when will you update your siggy ;-)

Sli showed spectacular scaling in AVP and crysis where it pipped the 6950 in all modes of cfx. I think tom's should have added more taxing dx11 titles like metro,lost planet 2 etc. to this test for more transparent results. Dirt2 would also had been a great addition.

F1 2010 is a title where nvidia cards don't perform well and thats why it scaling was poor.Same can be said for just cause 2 and its not taxing at all.

But avp although not being an nvidia title , scaled better in sli than crossfire. Its a true dx11 game.

Nvidia's architecture favours newer games and will see better scaling in them. Crysis is also quite UNBIASED imo. Maybe we will see similar results in games like BF3 and Crysis 2.

Vliw4 architecture of amd works wonders for older titles. But the advanced rendering techniques newer titles employ will definitely miss that fifth sp(special) and that can lead to a performance hit.

Nevertheless, two 6950's are definitely worth the attention cause of the lower price point and lower power consumption.

But we should see some more newer dx11 titles tested in sli and cfx before counting sli out.

J

looking at these results, i think hd 6970 cf would have humbled gtx 570 sli.

^^ Not in the first two titles i guess. But surely in the last three.

J

forget about 3-way scaling.

lets look at 2-way which is what most people do.

hd 6970 cf would have pipped gtx 570 sli. hd 6950 cf is only 2 frames less than gtx 570 sli in aliens vs predator. avp just had issue & didnt recognize the third cf card.

crysis is TWIMTBP game. but then we again look at 2560*1600 resolution, cf dominates sli always.

^^ 3 way scaling was the centre of this discussion and you've named the thread likewise. So why to forget it?

I guess 570 is kind of held back by its lower framebuffer. Thats why scaling takes a hit and we can blame nvidia for that. But the gf110 is a more capable gpu than both the caymans.

They should have included a gtx 580 sli against a 6970cfx. Heck, a 3gb model of gtx 580sli would have dominated all tests. If 6970 comes into picture, so will the 580 but the costs will increase as its 5k more expensive.

These guys didn't even include battlefield bad company 2.

---------- Post added at 03:35 PM ---------- Previous post was at 03:30 PM ----------

Joker said:
but then we again look at 2560*1600 resolution, cf dominates sli always.

No not always. At that resolution and above , framebuffer comes into play. Both 570 and 580 have blazing fast gpu's but are marred by lower framebuffer than the competition. So performance takes a hit at high resolutions. A 3gb 580 sli will decimate any cfx easily. But such cards are not readily available yet. The gtx 570 is also in desperate need of more framebuffer as its gpu is very fast and is held back by this aspect in multigpu configurations.

Nvidia should look into this.

J

scaling = scaling. two gpus working together whether they are individually faster/capable or not.

the point is, u are getting much better performance with $400 2 * hd 6950 compared to $540 2 * gtx 570, with a very very low lower power consumption. crossfire is the winner.

yup, nvidia should increase vram.

^^ Ya true but that doesn't conclude crossfire to be superior. Two 570's will be better in the long run and not only taking older games performance into account.

In india, the difference between 570sli and 69502gb cfx is 6-7k. Now thats a big difference and we can't deny the amazing value of a 6950. Like you said its cheaper and consumes relatively less power.

But not everyone will choose a 6950cfx against 570 sli. There are lot other aspects to look at and not only current and older game performance.

J

tomshardware have concluded crossfire in hd 6xxx series is superior. hd 6970cfx > hd 6950cfx >= gtx570 sli.

how can u say that two gtx 570 sli will be better in the long run when the caymans scale better with each other??

we also saw results in other reviews where hd 6970 sli was performing par with gtx 580 sli.

we are talking about scaling...u add a 2nd cayman, u get 90-100% scaling. not so when u add another gtx 570.

and 11.4 is even gonna improve tom's hardware result.

*hothardware.com/articleimages/Item1602/fc22.png

*hothardware.com/articleimages/Item1602/metro2.png

*hothardware.com/articleimages/Item1602/av2.png

and these are old results. things have improved for crossfire.

Actually it is not quite fair to compare multi-GPU set up to different multi-GPU sub systems. Basically one should only look at the difference achieved once a 2nd accelerator is installed. For SLI/Xfire the factors are quite different.

1. Screen resolution. The > than pure HD the better, will have less dependency on the CPU.
2. How much the CPU can be OC'ed. That is mostly mandatory for multi-GPU.
3. Driver scaling. This is probably the biggest factor.
4. Game scaling -- actually that it understand the multi-system.

Some of the games I play, multi-GPU makes jack difference, even if the Xfire logo is enabled on my game screen, i.e. showing both GPUs are spinning and processing.

Joker, by checking the results you have posted for CF and SLI scaling, It seems that AMD has done a lot of improvisations on their Catalyst Drivers. Even in the Tessellation heavy titles where DX11 is used, CF is showing more potential than SLI.
If you look at the results then it is clear that HD 6970 CF is beating GTX570 SLI in almost every cases. Now the price point of both the cards are same in india...around 21K. So HD 6970 is the clear winner.

HD 6950 1 GB version, available @ 14.5K can also be considered as one of the best options as the performance difference between 1 GB and 2 GB versions of HD 6950 is hardly noticeable and will offer performance slightly better than the GTX 570 SLI, which will cost you around 40K, compared to the 29K of HD 6950 1 GB CF.

@ joker

The way i see it buddy, sli is scaling equally well in newer games as crossfire. So no clear winner here. But pricing always makes the difference and as cilus pointed out, 69501gb cfx is an excellent choice for the price.

But its wise to pick two gtx 570's against two 6970 cfx. Only the low framebuffer is holding back the 570 a bit.

Check this link. My pick is the gtx 570 over a 6970 in both single and multigpu avatars.