I see your edits and, dang, I was hoping we could move the needle. Another idea:
Try running a game through game scope. You would add this line to the launch options in Steam’s per-game settings. Adjust to your resolution and desired refresh:
gamescope -W 1920 -H 1080 -r 60 -- %command%
https://github.com/ValveSoftware/gamescope
You can use it to troubleshoot all kinds of things.
Fwiw, I’ve had some very similar problems with GPU performance on my very weird setup. I’m going to share what I know and if that helps you diagnose, great. If anyone has suggestions, please reply.
My setup
My problem areas are very similar:
Performance (fps) degradation during gaming. Games slow down while temps decrease. VRAM and Ram are nowhere near full utilization. Hard drive is near room temp. CPU load is minimal. I have a wattage tracker at the wall and can see wattage drop. Steam games with multiple versions of Proton/ Proton GE
Vulkan-based compute workloads. Hence the weird GPU setup. Same deal. Start a workload at 100% throughput and watch it drop to 30% over the span of a few minutes. This is with artificial benchmarks where I can control workload variables
What ive found
LACT has helped. Setting a card to “Highest Clocks” has a meaningful difference
on some games, simply switching to the desktop and back resets performance. Works on Deep Rock
simply running vulkaninfo rests performance to 100%. I often resort to: watch -n .5 vulkaninfo
x11 behaves better but its not a complete fix
on x11 nvidia control panel “Prefer Maximum Performance” makes a big difference
I’m still figuring out how to get GPU p-states to lock to maximum. I’ve tried locking clocks but that’s not doing it
OS power saving set to lowest power tanks performance, but between balanced and high there’s no impact to this problem
disabling anything related to PCIe power saving in bios hasn’t made a difference
This is a real bummer for me and my gaming group. We had a couple of hundred hours in kf2
Please try this game Tyrian (see comments for Open Tyrian 2000). It has such great gameplay, upgrades, killer music and graphics. You can play 2 players with one person on keyboard and another on mouse. It’s great
You could use it to force resolution, HDR, vrr, refresh rate. It helped you isolate this not being a compositor issue.