Question About SLI Flickering in Vireio

[Syke408]

I know in the readme file it says that SLI may cause some flickering issues with some game. I accept that, but I am just curious as to why this happens? I have a GTX 690 and I tried to play Portal 2 with the Vireio Drivers and I had horrible flickering. I know people say that SLI causes issues like this with just stock games, but fortunately I have never had an issue with my 690. Any insight would be greatly appreciated, thank you in advance.

[Jademalo]

I'm not 100% sure, but I'm assuming it has something to do with how the 3D hijacks the renderer and it's interaction with alternate frame rendering?

Actrually... I have SLI 570s, but in all my testing of anaglyph 3D modes I've not had flicker. Is it something to do with the roll?

[cybereality]

I think the problem is that the Perception app is not rendering both eyes simultaneously. It is switching between eyes every other frame. So one frame it renders the left, next frame the right, etc. With SLI you usually are doing AFR (alternate frame rendering), so I imagine this somehow messes up the app's counter of which eye it is supposed to be. That is my guess anyway.

[Syke408]

Something interesting to note is that in Skyrim, Portal 1, Mirrors Edge, Half-Life, and Left 4 Dead the flickering does not exist, it runs perfect.

[drifter]

Hi guys, just to have confirmation for the last Vireio : Skyrim have no issues with SLI, but the performance gains are negligible (especially with ENB on) ?
Thanks.

[crichton]

The reason you get flickering is because when cards run in sli one card does a frame then the other card does the next frame . there is a bit more to it than that but that is the basic idea, but now nvidia have vr sli with the gtx 9 series cards. Vr sli alows one card to render one eye and the other card renders the other eye= no more flickering but its only available on 9 series cards. Hope this was of some use.