Hello, I’m using an RX 7900 XTX with an
MSI MPG 321URX QD-OLED Monitor.
Cable is HDMI 2.1, it supports 4k @ 240Hz, in fact I have a dual boot and I can set 240Hz in 4k without any issues with Windows 11.
However, here in OpenSuse Leap 15.6, I cannot see anything above 60Hz in my Gnome settings.
Any idea how I can unlock the 240Hz? Thanks in advance.
Hi there 
I found this while searching:
Instead of update-grub, you would use update-bootloader on openSUSE.
@pavinjoseph better to use YaST Bootloader to update grub…
Ah yes, forgot about that. That would be way easier 
Thanks guys =)
I did the whole procedure and I get VertRefresh 40-240 so I updated the bootload configuration accordingly. This is how it looks like now:
splash=silent resume=/dev/system/swap preempt=full quiet security=apparmor video=HDMI-A-1:3840x2160@240
I rebooted but unfortunately the new refresh rate still doesn’t show up. Maybe because I’m on X11? 
I tried on Wayland as well, it doesn’t seem to work there either. Any clues?
I could be off base but I’m not sure if these days AMD GPUs are still stuck on hdmi 2.0. If so, chroma subsampling might be a pain to set on x11 to 4:2:2 or 4:2:0. Last I heard HDMI Forum refused to let AMD add hdmi 2.1 still.
It’s kind of a pain as far as I know actually to tell if you’re using 4:4:4 or lower in first place.
Lazy solution… do you have a displayport cable?
How do you connect to the screen? Is this a straight HDMI to HDMI connection or with a dongle USB-C to HDMI?
If you use a dongle, some dongles do not support Linux fully.
@butcherbird I connected it with the DisplayPort that came with the monitor and it worked like a charm, thanks!
I had bought a very good HDMI 2.1 cable but apparently I didn’t need it. So the fact that it works on Windows 11 means that it’s probably a driver issue I guess.
In any case, I’ll be using the DP one now thank you all for your help!
Open drivers conflict with HDMI Forum policies. AMD proprietary drivers might help - if you really need HDMI connection.
I have the 321UPX + 7900XTX and KDE / AMDGPU / Wayland refuses to work over HDMI at 240Hz as well. I’m maxed out at 120Hz but have yet to try DisplayPort. I’ll try it and check back later if it works. 240Hz Full RGB 10-Bit mode works without any fussing in Windows, so it is not a cable issue. Might also attempt proprietary AMD drivers to see.
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