Fishing, I could still be the monitor OR the video card. Often the cards will have heat sinks in addition to a fan. Dust on the heatsinks will drastically reduce the effectiveness of the cooling despite the fan.
I'd suggest 2 things.
1. If you feel you are able: unplug power from the computer, open the case, using a small paintbrush and vaccume (plastic pickup tube), brush and vacuume any dust/dirt that may have collected inside. Especially pay attention to the fan and heatsink under it.
2. If you have another monitor, swap them out for a few days to see if the issue stays with your pc. If it does then it's likely the monitor, otherwise, the issue is with the monitor.
"Our greatest happiness does not depend on the condition of life in which chance has placed us, but is always the result of a good conscience, good health, occupation, and freedom in all just pursuits." - Thomas Jefferson