Steam VR Performance & SLI

[doublefrag]

It is futile whether I deactivate or activate SLI (2 x GTX 970).
The result is always the same.
My system is in the first third of the green part.

Does this means, that the HTC Vive do not support SLI yet?

[--ranXerox--]

I get the same result. Other sources say future patches will work.

[Walmart]

Quote from Rift community manager on their forums (and from my research, he is spot on for both Rfit and Vavle's):

"AMD LiquidVR and Nvidia VR SLI are special APIs from those vendors that allow game or engine developers to utilize multi-GPU in their specific titles. That means that (most likely) an engine developer like Unity or Epic would have to integrate these APIs into their engine, or a developer with a custom engine could integrate it themselves.

It will not, however, automatically make any game instantly support SLI/CFX, or gain any benefit at all. In fact, in many cases, having SLI enabled will cause VR games to not work at all (black screens, crashing, etc.). Even in the best case, the game will work with no performance benefit.

Maybe in the future this will change, who knows?"

So for now, SLI is not an option/don't get your hopes up.

[BOLL]

Alex from Valve comments on multi-GPU support in engines for VR here. Basically, it's good to have, it will save your developers from getting ill when developing, which is motivation enough. Then that it will be beneficial for the few consumers that actually have multi-GPU systems is just a bonus.

From some discussion on Reddit I was told SLI/Xfire wasn't even needed anymote, that multiple GPUs will be able to work for VR anyway as they work on individual scenes. I haven't read up on that myself, so I don't know. It seems like multi-GPU support is a work in progress thing so I'm not in a hurry to find out, my current system is also single-GPU.

It's definitely something that has to be built into the engines, like Walmart said, it's not happening automatically. For the SteamVR performance test you can supposedly try it already though! Add -multigpu to the launch options to try it out, including the dash.

[GlaucomaPredator]

I have two AMD cards in crossfire and the xfire is no utilized either. It's too early in the game to tell and most games on release will not tax the system anyways. I'm sure both AMD and Nvidia will patch their drivers to support multi GPU VR tittles as we go.

[Walmart]

Publicado originalmente por exist2resist:

I have two AMD cards in crossfire and the xfire is no utilized either. It's too early in the game to tell and most games on release will not tax the system anyways. I'm sure both AMD and Nvidia will patch their drivers to support multi GPU VR tittles as we go.

I disagree about games not taxing gpu's. That is the old logic when people did not care about frame rates as much (you could still play at less then 60fps, much less than 90fps needed here) and not running in 3d/two screens and at more then 1080p. Those times are gone my friends. Even an OC gtx 980ti (which I have) is not enough. Not even close. (Yes, some games you can run a 970, but those are the basic ones/Minecraft ish. A well optimized AAA (sort of) like elite dangerous, you have to turn graphics down, even with the best current single cards.)

[PopinFRESH]

EPIC has already announced engine support for GameWorks VR (with VR SLI) for the Unreal Engine 4. I haven't checked recently to see if it's been added yet, but I believe it was.

http://www.roadtovr.com/unreal-engine-to-add-nvidia-multi-res-shading-and-vr-sli-support/

I'm sure nVidia is also working with Unity Technologies to add support to the Unity Engine as well. The same goes for Crytek and the CryEngine.

As for AMD's LiquidVR, I haven't seen much regarding it however I'm sure they are probably also trying to work with the major engine creators to add support.

-PopinFRESH

[jay299uk]

Under Windows 7 this test only uses one of my HD7970Ms, under Windows 10 it uses both and the results confirm that.

[+25(mein 6000)]

NO money?

[Alchemist79]

Try putting "-multigpu" in the launch options.

[bmac1191]

I get usage in the high 70s with peaks in the 90s when I force sli rendering to #2 in the control panel. I cannot get the results because the benchmark crashes at the end. Can anyone confirm it increases the score?

Tested again.. sli disabled and recommended sli I get 150-160. Force rendering 2 I get 220-260 and average usage 80% both cards.

[alxtraxxx]

1x R390x gave me if I remember right a score of 6, with 2x390x cf enabled 11.7. I am using Win 8.1 so scores with equal setups running win10 will get higher scores. Btw didnt retest after last update

[O.M.H]

i have a gtx 970 Work?

[Knyght]

Duel video cards do not work for VR yet. Both Nvidia and AMD are both working on making each video card be able to render images for the lenses separately.

[bmac1191]

Publicado originalmente por Knyght:

Duel video cards do not work for VR yet. Both Nvidia and AMD are both working on making each video card be able to render images for the lenses separately.

Sli may work. VR SLI is another thing. I am getting an extra 100 fps by using the forced sli rendering #2. I'm sure that will depend on the game though.

I know nvidia's VR SLI must also be compatible or built into the game's engine so we probably won't see it for awhile. Hopefully it will be the standard by the time dx12 is more common.

[Stelly]

2x GTX 980 & 3930K @ 4.2GHz (stays at 3.2GHz during the test from low use)
without multigpu: 9.1
with multigpu: 8.5


Btw the "rendering each gpu to each eye" would be slower than the other techniques of today. A VR headset doesn't have 2 eyes, it has just 1 screen. For decennia the output pipeline has been to render horizontally and push out a frame to the OS. So you can't just make it split the frames in vertical parts and let them stitch it together. It would be slower and the incompatibilities would become hell.

Simply sticking with AFR and horizontal SFR would work just as well for VR output and would remain compatible with the other 99.9% outputs.