New Forms of SLIAA draw near.

[Kowan]

Thanks for keeping at them until they decided to give the users the choice, ChrisRay. (nana2)

[walterman]

Is this your version of April 01 ? ;)

[ChrisRay]

I posted this on the 31st... so no..

[hell_of_doom227]

So what SLIAA does? Can somebody explain, but please don't use too many technical words, just simple explanation? What is performance penalty of using, benefits over standard AA ?

THanks.

[lee63]

When can we expect these drivers ? ... will they coincide with the 275 GTX launch ?

I would like to try F.E.A.R. 2 with some SLi 32xQ AA :captnkill:

[Bman212121]

So what SLIAA does? Can somebody explain, but please don't use too many technical words, just simple explanation? What is performance penalty of using, benefits over standard AA ?

THanks.

The basic idea behind SLI AA is that one GPU is used to render the game, the other GPU is there to just perform anti aliasing. They are working together to give you a final product, but they do different tasks unlike AFR SLI where both cards are sharing a common workload.

So the only catch is that one GPU might be working at full speed to render the game, and the other one might only be working at half speed to do AA.

[Bman212121]

I have a question for you ChrisRay, has there been any talk of a GPU activity monitor? I was surprised to see that ATI has a gauge in the CCC to show how much GPU power is being used. This could be invaluable for trying to diagnose GPU issues.

[slaWter]

Is it possible to use those new modes with 2 GPUs or only with 3 or more?

[Bman212121]

Is it possible to use those new modes with 2 GPUs or only with 3 or more?

I was wondering the same thing. If the new method allows 3 or 4 card scaling then it will be interesting to know how it is implemented.

[ChrisRay]

2 GPU users will have access to SLI 16x, SLI 32x, and SLI 32xQ, SLI32x is the real gem. It gives 8x Multisampling, and 24x Coverage Sampling. Really low memory footprint. All the non quality versions have a 4xAA memory footprint. SLI 32xQ and SLI 64xQ use 8x multisampling.

[walterman]

So what SLIAA does? Can somebody explain, but please don't use too many technical words, just simple explanation? What is performance penalty of using, benefits over standard AA ?

THanks.

Basically, if you can run 4xAA with 1 card at 120fps, SLIAA allows you to run 8xAA at the same framerate. Each card renders a different 4x MSAA pattern, and they are combined at the end to produce an image with 8xAA quality. You do not gain any fps, buy you also do not lose any fps (little overhead at the end).

http://i42.tinypic.com/zmbbdh.jpg

@ChrisRay: Is the standard SSAA 2x2 mode supported now under SLI AA ?

[ChrisRay]

2x2 works with Quad solutions. But the positioning is very weak. I wouldnt even consider its presence. It doesnt touch much of the pixel. It does take 4 texture samples with Quad though.

[gstanford]

Just as an update to the 3dmark05/06 issue I mentioned earlier, I asked a friend for an ATi screenshot of the same general area.

http://img7.imageshack.us/img7/2561/3dmark06demo.jpg

You should be able to notice that the same sawtooth artifacting is present on the shadows with the ATi card, therefore this has to be a futuremark issue.

[jlippo]

Just as an update to the 3dmark05/06 issue I mentioned earlier, I asked a friend for an ATi screenshot of the same general area.

http://img7.imageshack.us/img7/2561/3dmark06demo.jpg

You should be able to notice that the same sawtooth artifacting is present on the shadows with the ATi card, therefore this has to be a futuremark issue.
The problem is in their Cascaded Shadow Map implementation, it has very good shadow resolution 5x(2048x2048), but the shadowed area is very large so the texels can be quite big in screenspace.

In addition to that, their implementation doesn't keep same shadow texel locations in the worldspace, so shadow texels follow camera and causes very annoying temporal aliasing.

The small light bleeding under the shadowing object comes from the fact that they cast shadows from the backfaces. (from lights point of view)
This is very traditional trick to make sure that there is no shadow acne on surface, but side effect is that shadow actually starts slightly after the shadowing object ends. (additional space comes from slight depth bias when rendering the shadow map.)

[gstanford]

Thank you for the explanation.

[MaxFX]

I can live without AA but since I got the GTX 285 I can finaly use some AA with my 24 1920*1200 monitor again :D

And of course one can see the defference between using say SSAA highest setting and
8Q / 16 MSAA. the difference is night and day and if you cant see it man you must really got a prescription glasses ;)

Beying able to use 64Q SLIAA must be a dream come true :D

[ChrisRay]

Here you guys go.

http://www.nvidia.com/object/winvista_x86_185.65_beta.html


http://www.nvidia.com/object/winvista_x64_185.65_beta.html

These support the new SLIAA and the new ambient occlusion feature.

[Bman212121]

(w/opics)