I upgraded my Dell Precision 3630 to F39 a couple of weeks ago. Since then I have an intermittent problem. Sometimes when I leave it idling a while and the screen blanks it will not wake up, neither from typing on the keyboard or moving the mouse. The keyboard and mouse are both connected with usb.
The only way to fix it, that I have found, bar power cycling it, is to switch to another virtual console. Typing - and then to get back to the initial display. Doing this the screen comes on and everything works fine once more.
If the problem is your monitor is waking up when you don’t want it to:
Some input devices look like activity. I’ve seen this be an issue for things like the BOINC client where if there’s a USB keyboard or mouse, the “only run on idle” will never get triggered because some devices always appear to be active on the USB. Might be worth unplugging the keyboard or mouse to isolate which one.
If the problem is that the monitor won’t wake up (“now” → “not”) then one thing that might cause something like this is using a USB dock and plugging too much into it so it draws more power than the port can handle, causing stuff to go unresponsive.
The now should of course be a not, sorry about that!
I think it is unlikely that it is an power issue. This is a server, not a laptop, and it worked without issues in Fedora 38 for the last six month or so. It is only when I upgraded to F39 that I started to see the problem.
Anyhow, thanks for the suggestion! I will try something to see if it has a power connection, maybe connect a usb hub in beween.