Cannot set refresh rate to 120hz

not option to set refresh rate to 120 hz on x11 desktop.
but on wayland 120hz works fine.

amd 7800x3d + 7900xt with lts kernel.

I am using KDE, and on x11 session, there is only option to set refresh rate to 60hz, but on wayland session there is an option to set to 120hz.

also, I am using a TV as monitor, and the TV is support 4k * 120hz, and the cable and the port are HDMI 2.1

What does xrandr command output? Do you use multiple monitors BTW? X11 can’t handle multiple monitors with varying refreshrate and resolution like Wayland can.

Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 16384 x 16384
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 1439mm x 809mm
3840x2160 60.00*+ 50.00 59.94 30.00 25.00 24.00 29.97 23.98
4096x2160 60.00 50.00 59.94 24.00 23.98
1920x1200 60.00
1920x1080 120.00 100.00 119.88 60.00 50.00 59.94 30.00 24.00 29.97 23.98
1600x1200 60.00
1680x1050 59.88
1600x900 60.00
1280x1024 60.02
1440x900 60.00
1280x800 60.00
1152x864 75.00
1280x720 60.00 50.00 30.00 59.94 29.97 24.00 23.98
1024x768 60.00
800x600 60.32
720x576 50.00
720x480 60.00 59.94
640x480 60.00 59.94
HDMI-A-1 disconnected (normal left inverted right x axis y axis)
HDMI-A-1-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-1-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-1-3 disconnected (normal left inverted right x axis y axis)
DisplayPort-1-4 disconnected (normal left inverted right x axis y axis)

Hmm, its not listed as an option. I would think the HDMI connection (or the cable) you use does not support 4k/120Hz over HDMI and would recommend DisplayPort if your TV has. But you say in Wayland it works? Can you confirm if you switch to Wayland 120Hz, that it’s 4k resolution and not 1080p?

yes, there is only on display(the TV) and on wayland session, the resoultion is 4k and I can set the refresh rate to 120hz, and it works.

The cable and the port are working fine, I used the same cable and port on windows, it recognized as HDMI 2.1, should support 4k 120hz.

I’ve researched a bit, but not sure what to do at the moment. I know with xrandr command you can set the resolution and refreshrate directly from commandline, but not sure if this is wise if the option is not presented in the list.

tried it, say current display not support 120 hz refresh rate…