8KX Lag / Latency Update

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I just wanted to share my findings while troubleshooting this problem that cropped up since upgrading from RTX 3090 to 4090, that post can be read here if you have not already:

8KX, upgraded to RTX 4090 from 3090, weird lag latency that I cannot rectify.

My troubleshooting consisted of:

  1. Fully uninstalling SteamVR which consists of the SteamVR folder and the steamVR.settings at ProgramFiles (x86)/ Steam/ Config (2x actually as the problem persisted after the first full uninstall)
  2. Disabling both MSI AB and fpsVR
  3. Disabling HAGS
  4. Ensuring SteamVR process priority is set to Very High Priority in Task Manager.
  5. Swapped the USB and Displayports that the Pimax 8KX is using.

The problem persisted, so having felt that I sufficiently ruled out SteamVR I pulled my HTC Vive Pro 2 out of the closet, reinstalled it’s associated software, did the fully set up to get SteamVR to recognize it, repaired the Index Controllers to it and wouldn’t you know it, THE PROBLEM EXISTS THERE AS WELL @ 120 Hz no less.

The same exact problem, moderate, nauseating latency and a frame skipping problem every 5-10 seconds (the frequency of which is reduced by closing MSI AB, fpsVR has no bearing on this).
So I did more sleuthing, using the search terms “VR Latency Lag RTX 4090” and wouldn’t you know it Varjo Aero owners are also experiencing the same problem and Varjo has even come out and acknowledged that there is a problem and that they are working on it.

Excerpt:

"On 10/14/2022 at 2:13 PM, Supmua said:So Pimax also stutters at max FOV? What’s the common denominator here, NVIDIA software?

I think the current line of thought is it’s a driver issue at high throughput…possibly DSC related. Which likely means an Nvidia fix ???
Edited October 14 by zildac "

So the problem is most definitely real, affects all headsets, and is most definitely related to the RTX 4090, most definitely implicating the display driver and possibly pertains to the way DSC (Display Stream Compression) works.

If Nvidia reps could investigate and acknowledge and open up an escalated dialog with Nvidia that would be much appreciated, as I stated in my original post, I didn’t need more raster or RT with a 3090 at 5120x144 2D, my main justification for blowing $1600 US on this upgrade was because my 3090 struggled with VR across many demanding titles. How Nvidia dropped the ball with this is beyond me.

Thanks for reading.

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If MCI off is on

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MCI?

It’s something related to DSC because the problem is not present with my Vive Pro 2 at 90 Hz but is present at 120 Hz. With my 8KX, reducing FOV from Large to Normal does not alleviate the issue. That reducing the refresh rate on the VP2 from 120 Hz to 90 Hz tells me that this issue is related to DSC.

Also, another bizarre issue is that it doesn’t matter if I change the resolution within SteamVR to 150% or 200% the GPU load is always 35% in VR Home (5800x3600 or around here). What is bizarre is that with my VP2, with an indicated 4380x4380 (this is what it is defaulting to at 100%, actual resolution is around 2500x2500!) and GPU load is at 65% in SteamVR and I actually have to reduce settings to lower than that of the Pimax 8KX in Assetto Corsa Competizione! Rough math puts the indicated resolution of the 8KX around 18k pixels vs maybe 17k of the VP2 but the load is way higher on the VP2! I have no idea what is going on here and I’ve already completely uninstalled SteamVR twice. Not sure if this is a Pitool problem or an Nvidia display driver problem or a SteamVR problem but if I had to guess I would say that it’s an Nvidia problem because I had none of these issues before upgrading to the 4090 and that’s the only variable that has changed.

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