[Solved] HDR "contrast" slider not working after switching graphics card Nvidia to AMD

[snix0bert]

I am using HDR on a Dell S3422DWG on Windows 11. I used to be able to control the brightsness in HDR via the contrast slider. iirc I passed some additional to the monitor via Custom Resolution Utility (see screenshots).

The benefit was that I could change brightness on the fly, even in HDR mode, via hotkeys.

After switching from my RTX 2080S to a Radeon 7800XT and a clean Win 11 install I can no longer change HDR brightness via the contrast slider. Enabling the contrast slider in Twinkle Tray works, but using it does not change brightness anymore (same goes for the brightness slider, which of course never did anything in HDR mode).

Might be an AMD driver issue. For me, the contrast slider was the main benefit of Tiwnkle Tray :) So if anyone has any idea...

[snix0bert]

I think I "fixed" it by disabling FreeSync Premium Pro and/or enbaling GPU scaling in Radeon Software. Changing brightness in HDR works fine as well as HDR and 144Hz.