The computer turns off Win 7, how to monitor because of what?

Question

Iron

After turning on the computer, it is not clear how it works - sometimes it turns off immediately, sometimes it works for 3 hours, half a day, a day and then turns off (without rebooting). When you try to turn it on, it can turn on immediately, or it can turn off immediately, even the screen does not have time to turn on. How to see why?

Answer 1

Does it turn on normally, or does Windows swear at an abnormal shutdown?
To begin with, stupidly: toss another PSU, then think.

Answer 2

Start - Control Panel - Administrative Tools - Event Viewer.
Interested primarily in critical events.

Answer 3

There can be many reasons. Check some of them:
-After turning off, do you have anything plugged into usb? like a flash drive. It happens to be short.
-Condo on the mat. board has failed. Here it is drizzling. Check out the look.
-Dust. So many times I met this because of the dust on the tracks.
-Look how things are with BP.
-It could also be a drizzling lake. Try other dice and watch
-Voltage drops. There are power supplies that automatically turn off when there is too much voltage in the network.