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#1 2025-08-03 20:38:35
- tetroi
- Member
- Registered: 2025-06-13
- Posts: 25
Accidentally switched monitor refresh rate to 180Hz, screen went black
Hello everyone,
I accidentally changed my monitor refresh rate to 180 Hz in KDE Plasma, and after that my screen went completely black. I switched to TTY2 and tried to use `xrandr`, but got the error:
Can't open display
I tried setting environment variables:
export DISPLAY=:0
export XAUTHORITY=/run/sddm/xauth_XXXXXX
(replacing `XXXXXX` with my actual file), but when running `xhost +` I got:
Authorization required, but no authorization protocol specified
Can't open display ":0"
Then, from `ps aux | grep Xorg`, I realized I needed to authenticate as root.
I logged in as root, and then `xrandr` started working.
`xrandr` showed that my current mode was `1920x1080` at `180 Hz`.
However, when I tried to switch the refresh rate to 100 Hz with:
xrandr --output HDMI-0 --mode 1920x1080 --rate 100
I got the error:
Configure crtc 0 failed
I wasn't sure what was causing this, so I created an Xorg configuration file where I added a mode "1920x1080_100.00" with the modeline obtained from `cvt 1920 1080 100`. Yet after applying it, my screen turned black again.
I am stuck now and don’t know what to do next.
If anyone can help explain why `xrandr` can't switch rates dynamically under NVIDIA, and how to properly configure the system for my monitor’s 100 Hz refresh rate (without causing black screen), I would appreciate it.
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#2 2025-08-03 23:17:04
- seth
- Member
- From: Won't reply 2 private help req
- Registered: 2012-09-03
- Posts: 75,180
Re: Accidentally switched monitor refresh rate to 180Hz, screen went black
https://wiki.archlinux.org/title/KDE#Un … lution_set
It is not very likely that SDDM itself is affected and even if, the resolution would not be preserved from your desktop session.
Remove the X11 config you created.
Fwwi, https://download.nvidia.com/XFree86/Lin … tions.html - see "ModeValidation" - you'd at least have to add AllowNonEdidModes but I recommend not doing that unless at least the current situation is under control and it has been determined to be strictly necessary to run specific modes.
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