KDE Plasma - Nvidia - VRR Fullscreen erratic monitor refresh

Issues & Assistance
1 
Operating System: CachyOS Linux 
KDE Plasma Version: 6.3.2
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.13.6-2-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 94.2 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 4090
Manufacturer: ASUS
Monitor: ASUS PG32UCDM

With VRR off, I get a steady 240hz refresh

IMG20250309120244
IMG202503091202441920×2560 313 KB

With VRR on, when watching video in full screen for instance, I get erratic refresh rate.

Video:
Erratic Refresh

This has been an issue since my switch to Linux early last year. Now, I am trying to figure out why it happens. Why is it doing this? Is it the GPU not ramping up?

2

I think VRR is problematic on the latest drivers right now. Well either that or it’s Plasma. Is your monitor connected via HDMI or DP?

3

It is connected through DP. I suspect the issue is probably related to the GPU being in a low powered state and not ramping up correctly when in full screen.

4

This sounds familiar actually. Can you install the closed modules and disable GSP to check if it fixes the issue?

5

Oh god I just noticed this, can you set NVreg_RegistryDwords=RMIntrLockingMode to 0 in /usr/lib/modprobe.d/nvidia.conf and run sudo mkinitcpio -P and see if it fixes this after reboot?

6

Oh god I just noticed this, can you set NVreg_RegistryDwords=RMIntrLockingMode to 0 in /usr/lib/modprobe.d/nvidia.conf and run sudo mkinitcpio -P and see if it fixes this after reboot?

It didn’t work. I installed the closed driver. How do I disable the GSP?

7

I suppose no one is going to answer my question. I have googled it and from what I can tell the tutorials are for Grub not systemd. I just don’t want to bork my system.

8
9

I confirmed that the GSP firmware has been disabled through nvidia-smi but the issue persists. Any ideas what else it could be?

10

Not really, maybe just driver or Kwin bug.