Test av nVidia SLI AA

[HKS]

Med 77.76 driveren aktiverte nVidia støtte for SLI AA for alle SLI brukere. [H]ard|OCP har testet det ut...

http://www.hardocp.com/article.html?art=Nzk4LDE=

 

 

 

Doing some performance testing, we found many situations where SLI 8X and 16X AA modes were playable. Half-Life 2, for example, is very playable at 1600x1200 with SLI 16X AA mode. Where these Antialiasing modes really come in handy is in CPU limited games. For example, a game like Flight Simulator 2004 lets you enable the SLI 8X and 16X AA modes to experience much better image quality with a very small performance hit as this simulator is CPU limited and not GPU limited. There are also many older games where performance is very fast on the GeForce 7800 GTX SLI setup. Therefore, these new AA modes should also work well in older games.

 

It seems for everything ATI announces, NVIDIA counters with “simple” driver updates. First, one key feature of CrossFire was its ability to use video cards with different BIOSs from different manufacturers. Well, SLI already allows you to combine cards that have different revisions of BIOSs, and, in Release 80 of ForceWare, you will soon be able to combine cards from different manufacturers. The second big feature of CrossFire was its ability to be application independent. That is, if there was no profile specified for a game, it would run in SuperTile rendering mode. Accordingly, with current NVIDIA drivers, you can now enable a global Multi-GPU mode of Alternate Frame Rendering 1 or 2, or Split Frame Rendering for every game that does not have a profile. Finally, CrossFire was going to introduce a cool technology known as SuperAA that combined Antialiasing sample patterns to create a higher quality image. Well, today NVIDIA is showing that they can do that too. The big difference between the two companies is that NVIDIA’s solution is available now while ATI’s solution hasn’t even hit the store shelves yet. NVIDIA even gained an advantage over ATI by having the SLI AA modes work in both Direct3D and OpenGL. SLI AA works on every single SLI configuration available form NVIDIA.

[MistaPi]

Siden Nv4x og G7x har en fixed sample mønster bruker de bare en offset. ATi derimot har programbar sample mønster og burde derfor kunne bruke samplene mer effektivt. Det skal bli spennende å se sammenligninger med cross fire super AA mode.

 

When I first got the info about SLI-AA, I was quite excited about it. I thought that NVIDIA slipped in something special with their GPU's without us noticing it, only to be brought out with this driver release.

 

While I still think that it is nice that NVIDIA did this, I am starting to think that it is more in fact marketing than any real performance feature. Yes, SLI-8X should give slightly better coverage over 8XS, but it seems that the offset and resolve pass for the two outputs from each GPU is not nearly as efficient as we were lead to believe. I have tested this out in some interesting situations, and I have found that running even an older title like BF 1942 at 1024x768 with SLI-8X is not nearly as fast as with running in AFR with 8XS enabled. I would say that it is about 30% slower off the cuff.

 

One would expect that both cards, doing the same frame, and applying 4X MSAA and having the frames blended on one of the cards would be less hardware intensive than each card running AFR with 8XS. That really does not appear to be the case.

 

While I was first excited about this, it is now starting to seem that these new AA modes are not particularly useful. I think that NVIDIA would have been better off including the unofficial AA modes 8X and 16X (available with Rivatuner) than with SLI-AA. I just don't think that the frame buffer on the 6x00 and 7x00 series can handle this type of functionality effectively.

 

This brings up another idea... ATI's Crossfire has the specially built compositing chip, and the super AA functionality there could in fact be significantly faster than what NVIDIA is currently offering with SLI-AA. While personally I like the functionality and integration of SLI a lot better than ATI's Crossfire, I think that in this case ATI could definitely have an edge. Of course, we really can't say for sure if this is the case because there are no Crossfire boards in any reviewers hands (that I know of at this time, but obviously Dave would have a better idea of this).

 

http://www.hothardware.com/viewarticle.cfm...cleid=707&cid=2

Endret 22. juli 2005 av MistaPi