How to diagnose a malfunction in the monitor?

Question

Iron

Hello. Please tell me how to diagnose the problem with the loss of signal for the monitor.
2 monitors are connected to vidyuhi gt 1060. One of them works stably, and the second turns off from time to time, while:
- there are no inscriptions on the screen about the loss of the signal;
- power saving and other functions that affect the power supply when idle are disabled
.
I tried to look at the system log to see what might be happening there, but I could not find anything similar to problems with the monitor.