I have a fresh install of CachyOS (was having similar issues on KDE Plasma Arch, however I was able to use the system with nomodeset without it freezing) and I’m trying to simply display out to a CRT monitor. Everything was working normally on X11 and I also have a dual boot with windows that works so it’s not an issue with the monitor or my hardware. My GPU is an Nvidia card.
To get the Live USB environment working I had to use nomodeset, nvidia_drm.modeset=0, and nouveau.modeset=0 kernel parameters.
After installing, I need to use the same 3 parameters to even be able to get to the SDDM login, however after logging in the system freezes and stops displaying anything. Without those kernel parameters I just get a black screen. The system works totally fine if I plug in a only regular 1080p monitor, however if I connect the CRT afterwards the system freezes.
The CRT is being connected via HDMI along with an HDMI to VGA adapter. The adapter in general is good quality and the EDID information I was getting when using X11 was picking up all the correct information including the model number and possible display output resolutions.
Any help here would be greatly appreciated, thanks!