My system behaves strangely during the first boot of the day:
when I start it I get no video signal on all my three displays. Everything else seems to work. When I press the reset button, I get a signal and can log in normally.
I’m sure I’ll get an answer in the logs, but I don’t know exactly what to look for.
That sounds like a hardware problem. It is possible that your graphics adapter isn’t getting enough power upon a cold boot, which would indicate a failure on one of the rails in the power supply.
Well, there’s always a point in time for hardware failure, unless it was already broken from when the machine was built, and power supplies are a known point of failure.
Some time ago my 2nd seat changed to the following behavior:
After booting the screen is dark. After a while I found out that I could log in without any problems despite the black screen by simply typing the password and then return. When switching from the login manager to the desktop, the graphics card is probably reinitialized.
Maybe you could try that. (At least it’s easier than a reboot)