Hi, Normally if you shut down the computer , it shuts off the computer power automatically. So, even if you switch on the power supply, you have to just tab the computer power button to start. Still, i could not guess what is your actual problem. Sometime it reboots and othertimes do not. Normally if you opt for restart , it will restart automatically.
Thus , let's say I'm right here the machine normally . I installed a program , did some update , I changed the user, etc.
If that asked about nine times to restart , restart normally , now has one time or another that it restarts , but not back .
I've spent a rubber contacts on memory , cleaned the cooler and HD .
Before I format was not so. So I think some setting screwed up Windows.
Bodily stays on the button "Power " and cooler running .