this post was submitted on 27 Jun 2025
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Strange graphical issue after a power failure (sh.itjust.works)
submitted 6 days ago by [email protected] to c/[email protected]
11 comments fedilink hide all child comments
 

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.

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[–] [email protected] 0 points 6 days ago (1 children)

Probably surge damage, honestly. Was your monitor plugged into the UPS or another surge protector, or just into a wall? Do you have any other cables connecting to your machine that aren't on the UPS or a surge protector? Also, a power strip is not equal to a surge protector.

As far as the cause, if you're seeing artifacts on screen past a certain position on the screen, that's the screen or cable, not the GPU. Your display adapter sends fully rendered frames to the display and wouldn't have a specific part of the frame that is corrupted if damaged. Anecdotally speaking, if a GPU has damage, it just won't work.

Also, you may want to check the capacitors on your card and motherboard to make sure they're all still flat and not bulging. If bulging, you took took surge damage and need to redo your cabling to make sure everything is protected.

[–] [email protected] 0 points 6 days ago* (last edited 6 days ago) (1 children)

Everything is attached to the UPS, both the computer and the main monitor are on the battery side. Why the computer was shut off on this UPS, I don't know. I might be switching brands of UPS.

If I switch it down to 60 or 100 Hz, the problem goes away entirely, so I don't think it's a hardware damage issue at this point. Like, I did a software update, I wonder if it's booted up with a slightly newer version of mesa or wayland or something that isn't playing nice.

[–] [email protected] 0 points 6 days ago* (last edited 6 days ago) (1 children)

Check your package manager logs to find out. Also check dmesg just in case.

Edit: you know what...try changing the outlet the monitor is plugged into and see if anything changes. Curious if the signal is weird or the rectifier got damaged by a surge. Maybe try the wall as well to find out if it still does it.

[–] [email protected] 0 points 6 days ago (1 children)

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.

[–] [email protected] 0 points 6 days ago (1 children)

I meant switch the power plug for the monitor to a different outlet.

[–] [email protected] 0 points 6 days ago (2 children)

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.

[–] [email protected] 0 points 6 days ago

That looks like a Wayland issue to me tbh.

[–] [email protected] 0 points 6 days ago* (last edited 6 days ago) (1 children)

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.

[–] [email protected] 0 points 6 days ago (1 children)

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.

[–] [email protected] 0 points 6 days ago (1 children)
[–] [email protected] 0 points 6 days ago

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.