Similar issue here. Intel i9-9900KS, NVidia MSI Suprim X 3090, MSI MEG Z390 ACE mobo, 32GB DDR-4000 C19 memory, 2TB EVO Plus NVMe SSD. Using a relatively fresh install (2 days old) of Windows 10 Pro. Previously used an HTC Vive (original) and had everything on Ultra, with no issues.
App: DiRT Rally 2.0 HMD: HP Reverb Virtual Reality Headset G20 (90.001 Hz, IPD 61.7)
GPU: NVIDIA GeForce RTX 3090 (188.8.131.5240) CPU: Intel(R) Core(TM) i9-9900KS CPU @ 5.1GHz
Delivered fps: 89.15 Duration: 38.9min. Headset was active: 33%
Median: 5.4 ms
99th percentile: 6.6 ms
99.9th percentile: 7.1 ms
frametime <11.1ms(vsync): 100%
Median: 3.7 ms
99th percentile: 5.2 ms
99.9th percentile: 7.4 ms
frametime <11.1ms(vsync): 99.9%
Reprojection Ratio: 0.8% (for Index/Vive/VivePro headsets only)
Dropped frames: 691 or 0.3% (for Index/Vive/VivePro headsets only)
Max. SteamVR SS: 100%
Render resolution per eye: 3160x3088(by SteamVR settings, Max.) (HMD driver recommended: 3159x3089)
The Dirt2 Rally Steam VR graphics settings are at their lowest. CPU usage averages 10% with a short peak of 45%. GPU usage sits at about 62% with a short peak of about 76%. It's all well within limits, I'm getting very nearly perfect 90fps indicated yet I regularly get stutters in game. In game, fpsVR manifests these stutters as purple 'spikes' in its GPU frametime graph, and I see a stutter. It happens regularly and is easily repeatable. But the game sees 89.15 fps average with the longest frametimes at 7.1 and 7.4ms, which should be a complete non-issue and not noticeable, but fpsVR records 691 dropped frames after 40mins play. In game though, it's like someone pressing pause for a tenth of a second, really throws off the immersion and is enough to cause accidents!
I'm using nVidia drivers 461.40 which to my understanding should have incorporated the VR stuttering hotfix driver 461.33. Suggestions elsewhere have said this might be an issue with reprojection settings, but I'll try the DX12 fix mentioned above.
Any suggestions welcome.