Windows 7 Computer reboots sometime after monitor is powered off

[sunrisecc]

I get Windows 7 rebooting on its own under the following condition:
I power off the monitor and sometime later when I power it back on, I see that I am at the logon screen.

If I never power off the monitor, Windows does not reboot on its own.

I did change the power supply. sfc finds nothing. There are no new video drivers. My screen saver is set to 15 minutes (using the black screen) and the power saver option turns off the monitor after 60 minutes. All of this works as advertised without problems until I power the monitor off physically.

The error log just reports that an unexpected shutdown has occurred. I am using a new UPS which is working well.

Should I replace the video card?

Monitor Samsung PX 3270
Video MSI R4550

 

[Pauli]

Not trying to sound like I'd ignore your problem - which I don't, as I have some issues with standby etc. myself, my monitor goes off by itself... then it suddenly starts again... occasionally. It comes and goes, you know?

The only "advice" I can give is, live in peace with your computer, and do NOT turn off your monitor physically. However, if you have warranty for your computer, you could take it to service. Otherwise, this seems like an oddity of it. No offense, ok?

 

[sunrisecc]

I am now convinced it is the motherboard. Either a capacitor or the motherboard itself needs replacing.

Thank you for your reply.