PC Graphics

[pi]

Hi everyone,

started using a 7900 XTX for VR development (before people jump on me as seems common in here, I bought this card deliberately knowing about existing issues, since I develop games for VR I still need to ensure the best compatibility I can with different vendors).

Unfortunately SteamVR in "Direct" mode exhibits a strange behaviour wherein photon latency appears to be too high. Framerates are fairly smooth (I do know of the existing issue about performance, this is distinctly different - it occurs even when running at stable 90 FPS), but latency is quite horrible. Shaking my head drags the world behind, quite motion sickness inducing. It seems at least 2 frames behind I'd say, not entirely consistent, but also never 0 (as it should be).

System Info:

• Powercolor Hellhound Spectral White 7900 XTX
• AMD 7950X3D
• Gigabyte X670 Gaming X AX, latest BIOS (F7b)
• 64 GB DDR4-5600, 2 sticks, dual channel
• Vive Pro 1, DisplayPort
• 3 displays with different refresh rate (disconnecting all but one does not improve the situation at all however)
  • on that note, 80W idle power draw is indeed too high, but that's a seperate known-issue too, I know

What does fix the issue:

• Switching to "Extended" display mode (not viable because of vastly worse performance)
• Using a different AMD card (RX550) on the same driver and system otherwise (rules out a lot of "system misconfiguration" options, I did not change anything in the driver, windows or app settings, only swapped cards and rebooted)

What didn't fix the issue so far:

• Updating AMD graphics drivers (tried the past few versions up to the current Adrenalin 23.5.2)
• Updating to beta drivers via "Beta" channel on Windows Insider (currently running 23.20.00.11)
• Resetting driver to defaults
• DDU reinstall
• Setting various windows Graphics options (e.g. optimizations for windows games), CPU related options (it is not related to higher latency from the X3D die for example), and various driver options (Anti-Lag, FreeSync on my non-VR displays, etc...)

If this is a known issue as well, or anyone else has experienced this (or perhaps even fixed it?) let me know. Otherwise this is my bug report about it

If required, I can provide more details or profiling running on my machine, I'm set up with developer tools.

[IvanHell]

Hmm this sounds just like my Experience , I have 2 VR head sets (Quest 1 and Pico 4) I even have a NON game person testing both . He had a severe motion sickness with the Pico 4 (i did not) as opposed to the Quest 1 (both Headsets where running the same Resolution ) .

But i did see that my Frame times where close or even over 20ms in HF Alyx on High Fidelity settings . Did try to disconnect all monitos witch helped with the frame times (about 1 ms) , Still disconnecting monitors does help a little but the VR is still making the GPU render 1 frame 2 times . 

I still think the problem is with the architecture , chiplets do not work together as good as a single die . 
I do with i am wrong !

[pi]

Noting here that driver 23.7.1 does not change behaviour at all, even though claiming to have some VR-related fixes. Extended-display-mode rendering works in this version with good latency, performance is okay, but it still comes with a bunch of drawbacks that I'd rather not have to work with.

[gmazza]

One thing I've noticed is dropping the display frame rate from 90 to 60 on an HP Reverb G2 smooths out a lot of freezing and latency issues when it can't maintain a solid 90 fps due to demands. This has worked in both MSFS and Euro Truck Sim 2. Not sure if it would be reflected in your testing, but it seems like when the card starts to struggle to meet the display rate, something happens where it falls apart. Very strange...

PS - I've seen a big improvement with the new drivers, easily double the performance wit

[IvanHell]

Have been testing bunch of games , even some Scenes in a Engine base for VR . Latency is still as hilly as the Balkans FPS is mostly stable but FTs are all over the place from 10 to 22 ( most of the time ). I guess a Chislet design was too early.

AMD better do more extensive testing , I'm willing (and others too) to wait for a better product instead of a broken one . Take note from intel ... 

[pi · Accepted solution]

It turns out this specific issue is caused by SteamVR and not AMD directly (although it might be happening _because_ something in the AMD driver is broken). This reddit thread from a few months ago mentions the same issue happening for some 4090 users, and the portrayed workaround (using `vsync_to_photons_increment`) applies to the 7900 XTX in my case too. Tracking and latency are now perfect even in direct mode, as long as I apply the override everytime I start SteamVR.

I made a little script to set the value automatically. Either Valve or AMD still need to fix this proper, but at least I can use it now.

On AMDs side this might be caused by incorrect reporting of vsync timings from the driver API, unsure. For the 4090 series, apparently the fix shipped as a SteamVR update, not a driver one, which would point to the ball being on Valve's side. I will try my best to report the issue there too.

Edit: Based on the reddit post, perhaps the AMD driver is not or incorrectly implementing the equivalent API for `NvAPI: VSync2Flip`?

[pi]

cc.@Matt_AMD since you requested to be pinged on other VR related issues in the massive thread. This might be a good thing to forward to engineering

[Finn1337]

Could you share the script?

[pi]

https://gist.github.com/PiMaker/73c3b27f35c8293716fd50fa2749a135

[Finn1337]

Thanks homie

[IvanHell]

OK it seems like the 23.7.2 fixed my issue and any game I've tested (even unofficial) are running at about max FPS and at about 7-10ms , still I see some stuttering it's not easy to catch in a fastpased game with a lot of movement. 

So my results where .

Half-life Alyx- some stuttering at 90 Hrz most Frame times at 7-10 (stuttering not seen in Frame time graph ) 

Robo Recall - Nothing to note here , runs perfectly. 

Beat Saber - runs a bit better on songs with video on the wall (that is a perfect performance for me)

Valve's The Lab - Perfect performance at 5-8ms FT

As for the unofficial games/engines/scene builders - Better performance in loading world when turning fast (almost not noticeable loading of new chunks or view )

Still there is a bug with the lights in Unity Engine games , hidden lights shine through an unloaded textures for brief moments when moving in the world. 

T.L.D.R. New update (23.7.2) fixed my issues with VR performance (as far as I know it about 80-90% of the performance of the card ) 

[Lesnightfly66]

While it has certainly been some time since that GPU has come out, it does appear our minimum requirements for use with Meta Quest Link does not list the 7900 XT card as currently supported. This means the compatibility of that specific card has not been confirmed, and may not allow for the full functionality. As our teams work to test out and confirm the best set up to use, we look forward to

This is an official reply from Meta