Question Faint horizontal lines on monitor have randomly appeared (only on high refresh rates)

May 23, 2023
Hi all, I have a Pixio PX277P with a 3080Ti. Today, faint dark horizontal lines suddenly appeared on the monitor, covering everything (games, windows, desktop, etc). They're semi-faint, dark, look to be 1px wide, and completely uniform covering the wholes creen. I have a second monitor which doesn't have this issue at all. There's no screen tearing or any other visual issues. However, the lines disappear completely when I set the monitor's refresh rate to 60Hz. If I set it to either 144 or 165, they reappear.

It's connected via a Displayport cable. I've tried swapping the cable for a different one, swapping cable ports, updating GPU drivers + Windows, power draining the PC, disabling Gsync/freesync, trying different resolutions. When it first appeared, it lasted for maybe 30 mins then went away again for about an hour, and has now come back.

Anyone have any ideas on stuff to try?