Why does my 165Hz monitor flicker above 120Hz on Linux?
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MellowPine47
I'm trying to use my 165Hz monitor at a refresh rate higher than 120Hz on Linux, but the display starts flickering or behaving incorrectly whenever I select a higher rate. My graphics card is an AMD RX 6600, and I've tested Linux Mint, CachyOS, and Bazzite with the same result. The monitor is connected over HDMI at 1080p. I'd really like to use the monitor's full refresh rate instead of being limited to 120Hz. What should I check?
Answers
The HDMI connection is the first thing I’d investigate. High refresh rates can be more troublesome over HDMI depending on the monitor, cable, and port. Try a proper DisplayPort cable and connect it directly to the RX 6600. Also check the monitor’s menu for an option such as high-bandwidth, HDMI 2.0/2.1 mode, or enhanced mode.
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It would also help to know whether you’re running an X11 or Wayland session, since those are different display systems in Linux. You can usually choose the session from the login screen. Test both if they’re available, and compare whether the monitor behaves differently over DisplayPort.
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Try reseating the video cable on both ends and then rebooting. A loose or marginal connection can work at 60 or 120Hz but become unstable at higher bandwidth. If possible, test another cable and another port as well.
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MellowPine47: It’s currently HDMI at 1080p, so I’ll try to find a DisplayPort cable and test that.