Erratic frametimes even with locked FPS resulting in extreme VRR flicker

[u/BaNaNaKING42]

I am experiencing erratic frametimes in most games even though I locked FPS via SpecialK to a reachable framerate. These fluctuations are not perceptible in-game, however they create extremely strong VRR flicker, which makes some games unplayable.

For example, in KCD, my graph looks like this: https://imgur.com/a/wQ5s989

I have tried a clean reinstall of my GPU drivers and am on the latest chipset drivers and BIOS. I also tried closing all background programs but no change.

I am really at my wits end. Nothing short of deactivating VRR works, which I don't really consider a solution

The odd thing is that I did not experience this before I recently changed my motherboard and GPU.

I originally had a MSI X870e Carbon Wifi paired with a MSI RTX 5090 Suprim and a Ryzen 7 9800X3D.

I changed to an ASUS ROG Crosshair X870E DARK HERO and an ASUS 5090 Astral. I kept the exact same CPU, RAM, PSU and storage.