What is the word on Unity SLI and/or Crossfire support?

Unity Engine
1

I have a simple question with apparently no documented answer.
I want to make a game in unity. I have two videocards (nvidia gtx 970 in SLI (“Scalable Link Interface”)).
How do I make my Unity build run in SLI (use both videocards)?

  • What exactly does unity (5) support at the moment?
    Does it support nvidia physx in sli? (does it send all physx computations to the second gpu?) What does that include (in terms of rendering)? Just compute shader special effects like fluid simulation / particles? Is there any guide on what specifically I must do to send compute shaders to another gpu?
    Anything else in SLI?

  • I saw a reddit post which says that if and when unity 5 will support DirectX 12 (this december?), it might also come with unity support for Split Frame Rendering. Any word of confirmation on (at least plans for) that? Will SFR or AFR also work with Oculus / VR? (as far as I can tell you should be able to send the whole game (oculus or otherwise) to both gpus and do SFR or AFR…)

  • Ideally I want Split Frame Rendering or Alternate Frame Rendering, but can we do anything else at the moment? Is there any conceivable workaround to for example do deferred rendering shadow calculations on the second videocard?

  • What about Oculus / VR in unity and SLI / Crossfire? You’d think it was important to make unity render one eye with one videocard since VR is so demanding (needs more than 2x the resources of non-vr).

Cheers.

PS: Does the Unity Profiler provide any info on what exactly is each videocard busy with? E.g. “PhysX is running on GPU#2 and here is what it’s doing: …”

2

No idea about SLI/Crossfire support - but PhysX in Unity is CPU only

3

I realize you can just get Nvidia’s drivers to force render anything in AFR with more or less success. (I say more or less based on the nvidia onscreen green bar indicator and what you’re looking at in game)

And I saw just now that yesterday Nvidia released a Game Works VR SLI driver ( https://developer.nvidia.com/virtual-reality-development ) which is supposed to render each eye in one videocard.
It’s a beta release, I’ll check it out.

[EDIT] The Game Works VR is an API not a driver. So unless unity integrates it, it’s no help for unity applications.

And I’m not sure at all about Crossfire.