What is the bottleneck for VR graphics?

[lovemesomespeed]

I'm looking to build the ultimate sim rig, and I'm wondering what the bottlneck is in terms of being able to run VR at the absolute highest graphics. I've got a Reverb G2 on pre-order, and with the increased resolution, I want to be able to absolutely max it out.

So, if you had an RTX Titan, or two 2080Ti's running together with SLI (or these same scenarios with whatever NVIDIA is going to release in a few months), would the bottleneck now be that the programmers didn't put that much detail in the VR version of the game in the first place? Or would your CPU be the bottleneck? Or would running an RTX Titan (or the next generation of this card) or even two Titan's in SLI take VR resolution to the next level?

And before anyone ridicules me and says "Spending x-amount on your GPU alone is totally stupid...", so is spending over $1 million on a hypercar, but people still do it, and it's awesome...

 

[Showerhead]

I'd be interested if you can find anyone who has tested it properly but from quick googling the 2080ti is still going to be the bottleneck. I found someone with a pimax using it in ACC and it averaged 93 fps so still quite a bit below the refresh rate of the headset. Still plenty high enough to play however

 

[BrightCandle]

VR doesn't work with more than one GPU at all. Well VR does sort of in about 7 games but none of them are sim racing games. The bottleneck depends on the game, but generally VR bottlenecks mostly on the GPU long before anything else, if nothing else you want as much supersampling as you can get so you can utilise that GPU performance even in games that are lighter. So getting as much GPU in there in a single card as you can reasonably afford is the route forward.

Saying that however some of the sims are quite CPU bottlenecked, usually on a single core. Assetto Corsa is one of those but its thankfully usually above 90 fps and with CSP+Sol you can utilise the GPU better and reduce the CPU bottleneck a bit but you need a good CPU as well. ACC I suspect is CPU limited completely and just can't get to 90 fps regardless of what you do resolution wise so no CPU you can buy can get enough performance in ACC.

So I think you kind of need an overpowered machine generally for VR especially in Sim racing where a lot of the games are ports to VR and tend to have quite high requirements. By all means get the single best GPU you can but also that last 5% on the CPU could matter as well, more clockspeed and IPC because the sim games tend to be poorly written and often single-thread limited. This is generally true for VR games actually, Unity engine and Unreal both seem to usually have low amounts of threading for VR games.

It is a bad time to buy a GPU however with new cards expected this autumn there is a good chance a 2080 ti is a good 30-50% off-peak performance in a couple of months time and that the $1200 you spend would get you a lot more in 2 months time or that level of performance would be $700. But definitely don't buy multiple cards, its not going to do a thing in VR.

 

[TedBrosby-]

Depends on headset and sim.
index or Pimax and your bottleneck will be both the GPU’s and the sim developers VR implementation.
Rift S or CV1 or WMR or original Vive and the bottleneck is the lower resolution of the headsets.
The best performing sim in VR is iRacing (looks amazing out of box and runs amazing) followed by PC2/AMS2. After that rFactor 2 and then AC and then ACC. ACC can look okay but it takes a lot of work to get there. Thankfully with ACC you can use a custom json file for VR and switch between that or high/epic if you wanna drive non VR. Worst VR implementation is hands down R3E. Takes hours to dial in (if you’re running a Rift or other non Valve headset) and you cannot easily switch between VR and monitor.

 

[diablo2112]

Unless the game engine was specifically written to take advantage of SLI (multiple cards), you won't see any advantages at all. And, all the tests I've seen show the common sims weren't SLI optimized.

Wait a few months. The 3080 Ti/3090 will be a significant improvement for 4K/VR gaming.

 

[Deleted member 197115]

Surprisingly I had no issues whatsoever dialing in R3E, in fact just followed this simple guide, except have Shadow Split on and using 250% Steam SS.
What is the problem though on some tracks, like Nord 24, is time multiplier, it can kill even strongest PCs.
Not a typical feedback, but my favorite VR sim at the moment in ACC, photo realism of this title just kills everything else, unfortunately only 60hz WMR mode for me in order to retain high image quality.
AC with SOL/CSP can be gorgeous too but shows its age already.

 

[vinnefreerider]

Surprisingly I had no issues whatsoever dialing in R3E, in fact just followed this simple guide, except have Shadow Split on and using 250% Steam SS.
What is the problem though on some tracks, like Nord 24, is time multiplier, it can kill even strongest PCs.
Not a typical feedback, but my favorite VR sim at the moment in ACC, photo realism of this title just kills everything else, unfortunately only 60hz WMR mode for me in order to retain high image quality.
AC with SOL/CSP can be gorgeous too but shows its age already.

Andrew,

this OpenComposite thing is very interesting... I'll gonna try it on AC...

Have you ever tried?

Thank you for these informations

 

[Deleted member 197115]

This is for Oculus to bypass SteamVR, correct? I am on WMR so that wouldn't work in my case I am afraid.
I have compiled some AC VR guide a while back, check if it's any helpful.
And here's one for ACC (readme inside zip).

 

[vinnefreerider]

This is for Oculus to bypass SteamVR, correct? I am on WMR so that wouldn't work in my case I am afraid.
I have compiled some AC VR guide a while back, check if it's any helpful.
And here's one for ACC (readme inside zip).

I think the OpenComposite works with OpenVr too.. I'll gonna check this today..

Your AC VR Guide is great! I know it, thx

Ah, yesterday I tried something different on my settings, I disabled the Intel EIST on BIOS.
Apparently it helps to reduce the stuttering...