System is Fedora KDE, graphics card is an Asrock Radeon 5900GRE, display is a Gigabyte M34WQ (1440p ultrawide 144Hz refresh rate) attached via DisplayPort.
Despite being on a UPS (which…we’re also going to have to talk about) my system was apparently shut down by a thunderstorm. I booted it up, and the display was acting glitchy. I would get two mouse cursors, and below the mouse cursor the screen would go a solid color, as if it was glitching on a pixel and then displaying that from there down.
Switching to a lower refresh rate made the problem go away, I’ve switched back up and it seems to be alright. A second 1080p60 monitor attached via HDMI didn’t show any problem.
Some googling didn’t turn up exactly what I was experiencing. Can anyone help troubleshoot this? It seems okay for the moment but I’m hoping I don’t have a wounded GPU.
Switched the socket on the GPU the DP cable is plugged into, I think I see the same problem. It’s only been a few seconds, I haven’t seen the “lower portion of the screen from about the mouse down goes one color” thing yet but I have been seeing a double mouse cursor. This goes away completely when setting the frame rate down to 100 (says 99.98 in the KDE settings menu).
Not sure what I’m looking for in package manager logs or dmesg.
I meant switch the power plug for the monitor to a different outlet.
Right now, if I set KDE’s settings to 100 Hz, everything looks fine. If I set it to 144 Hz, sometimes I see a double mouse cursor. I get a second cursor about an inch to the right of what seems to be the actual cursor.
Explain how a problem with the UPS will cause that symptom.
That looks like a Wayland issue to me tbh.
Apparently it’s an AMD firmware issue.
When you increase your resolution, your monitor switches power modes. At a higher refresh rate, a dirty power signal can cause artifacts on the screen. Usually this means that you’d see bit crawl on the edges of the screen, but it could show display artifacts like you describe depending on the panel controller.
If your UPS took a hit during a thunderstorm, you could easily have a damaged rectifier in the UPS. That rectifier is responsible for smoothing the power signal coming out the ports on your UPS. A dirty signal can do the above as I mentioned.
You wouldn’t notice a problem on your machine because it’s own PSU smooths those signals out, but a monitor doesn’t have that.
I’m still skeptical that it would cause problems that minor, prior experience tells me it would do something like work fine at low resolution and show no picture or boot loop or something at higher resolution, but for the sake of troubleshooting when there’s less convective activity on the radar I’ll try plugging it straight into the wall.
It’s not bulletproof, but I’ve seen it live, so it happens. Proof:
https://forums.tomshardware.com/threads/monitor-shows-artifacts-for-a-couple-minutes-then-works-perfectly-fine.3518801/
Okay, it’s not the power supply. Found this on the Fedora forums: https://discussion.fedoraproject.org/t/weird-cursor-issues-on-fedora-kde/156413/8
Apparently the power failure just happened to coincide with a kernel update that causes a bug with AMD firmware; people are reporting the issue with higher end Radeon 7000 series cards using high refresh monitors attached via DP with kernel 6.15.
My uname -r output: 6.15.3-200.fc42.x86_64
So I can either learn how to revert to kernel 6.14 on Fedora, I’ve never messed with it before, or live with 100Hz like a bronze age slum rat until they push a fix.
The further mystery is why a momentary power loss took down a PC plugged into a UPS. It has one job, that it apparently didn’t do.
👍