emoneysteiert Please do a clean uninstall and reinstall of both graphics drivers, as described here:
https://crinrict.com/blog/2019/02/clean-re-install-of-graphics-drivers-with-display-driver-uninstaller-ddu.html
Remove the Nvidia driver first, then the AMD driver. Reinstall only the Nvidia driver, while your computer is still offline.
If that doesn't help, click Windows key-X, select the Device Manager, expand Display adapters, right-click the AMD device, and disable it. Restart your computer again and test.
If that doesn't help either, please create a fresh dxdiag and post it here.