Not typically what you’d think of when somebody says “mom’s computer,” but this is exactly what happens when my GPU overheats. Monitors stay on with black screen and no response from keyboard input.

Post system specs here just to be safe. If it’s an older machine, there could be various hardware failures. “Monitors” makes it sound like a desktop, but you should clarify just to be safe, and perhaps indicate if has PCIe slots or is more of a mini PC.

Also, what do you mean by “monitors going dark”? Are the backlights on, or are they absolutely dark?

Thank you all for all the suggestions, I don’t live with her so I’ll have to try out all your suggestions when I visit / if she has time for a Remote Desktop session with me.

Since it wasn’t mentioned yet: Make sure secure boot is disabled. It can prevent the GPU driver from loading correctly.

It could be a hardware issue. I’ve found that if the screen drivers fail it usually switches to a text console or reboots into one. Assuming you have a laptop, does wiggling the screen make any difference. If its a desktop, try wiggling the power connector or video cable (both ends) and along the cables, sometimes stress can break the wires in the cables if they go around a bend.

Does it have Nvidia graphics in it?

I’ve had that issue on computers with Nvidia graphics, and the solution, in my specific case, was to install the latest proprietary Nvidia drivers.

If you’re ever present or have remote access to her network, make sure sshd is enabled, and try to SSH into it to see what happens.

Q’s:

1. Is this a laptop or desktop?
2. If Desktop, what kind of cable is the monitor connected with?
3. See if you can get dmesg output (needs to happen during the event, but the machine is still accessible - hence ssh above)
4. Does the monitor have its own power saving settings?

Check /var/log/syslog, dmesg, and /var/log/auth.log

Like the others suggest, try setting up ssh access so you can see what’s happening.

If you use ssh and login, I’d recommend using top or htop and maybe diskhogs and see what’s up

Can you still SSH to the machine when it’s in that state? If you can it’s likely to be a problem in the graphics stack, if you can I’d probably start by running memtest86+ for a full cycle to rule out memory issues. After that, checking things like CPU temps would be good.

Assuming that’s all good, check for anyone else reporting issues with the same motherboard, CPU, GPU, or other components

Good luck, this sort of thing can be quite frustrating to get to the bottom of.

From “the monitor goes dark”, it would be helpful to split monitor issues from computer issues. When the computer becomes unresponsive, do any “non-monitor” functions still work? Does the DVD-drive tray eject or does audio continue to play? Any other details? Do any other lights on the computer stay on, like keyboard and mouse lights?

If the issue is primarily the monitor, then splitting between the physical monitor and the video card would also be helpful.

How old is the hardware?

When you say “nothing is logged”, is the hard shutdown logged or anything after the time of the event? Or does “nothing is logged” mean the normal items are logged, but nothing of interest is logged? Some issues, especially hardware ones, stop the computer from logging.

Story: I once had a 15+ year old computer do something similar. The screen would go dark, but the lights on the keyboard stayed on. I had to hard power the system off and sometimes on boot the monitor wouldn’t work. A monitor swap didn’t fix the issue, but a USB video card did. The video card had failed. (Looking up what I think the interconnect was, the system may be 20 years old at this point.) NOTE: The system was not functional long term with a USB video card due to how the BIOS in the system handled the two video cards.

Is it sleep mode not waking up?

Set up SSH on it and make sure you’re able to connect into it while it works normally, that way when the issue occurs you can do a quick test to see if the system itself is still up and running.

I’m not on Linux Mint / Cinnamon but I’ve occasionally seen GNOME sort of hang/freeze so the screen display becomes non-responsive. After a couple of times of that happening I ended up setting up SSH on the system and configured a SSH client on my phone so I can do a SSH connection into the desktop and force-logout my user (which apparently fixes the issue and brings my main desktop back to a normal login screen). I haven’t quite figured out if it’s Gnome issues or something to do with my Nvidia GPU… though with Linux if Nvidia is involved then it’s usually Nvidia, ugh.

Also if you’re physically at the computer when it happens try unplugging/replugging in the monitor cable, maybe there’s something wonky going on there or with the display connection.

Just some ideas to help you along :)

You could try this https://feddit.online/post/1359926#comment_6688858

Doesn’t sound like this is screen blanking as it happens during use but to rule it out you could temporarily disable that with xset -dpms and xset s off on X11. https://wiki.archlinux.org/title/Display_Power_Management_Signaling#Xorg