SDDM sets wrong resolution


I’m running OpenSUSE Leap 15.3 on my workstation. My video card is an NVidia GeForce GT710, and I’m using it with the proprietary x11-video-nvidiaG05 driver from the repositories. I have two 22" monitors which I’m using in twin view mode, and my desktop environment is KDE Plasma.

KDE’s resolution is correct: 1680x1050 on each monitor. Unfortunately SDDM doesn’t seem to get the resolution right. The login screen vaguely looks like a 1024x768 resolution with wrong proportions and all blurred, and it’s rather ugly.

I suspected my GRUB setting to be at fault, so I tried to replace the autodetected resolution by various hardcoded resolutions, both in 4:3 and 16:9. To no avail, SDDM stubbornly shows up in the wrong resolution.

I’m slowly reaching a point where I want to put my fist through the screen. But before doing that, I thought I’d rather ask you guys.

Any suggestions ?

I’ll answer this myself, since I just found the culprit. This workstation has been running Leap since version 15.0, and initially it had a pair of 19" 4:3 monitors with a maximum resolution of 1280x1024. This resolution was hardcoded in /etc/X11/xorg.conf, probably generated by the NVidia setup script back then. I edited xorg.conf and corrected the resolution, and everything’s perfect now.