I going to assume that by "cpu" you mean computer, not central processing unit.
I would like to help you, but I need more details before I can diagnose an issue. There could be a million and one things wrong with your computer at this point, what else is going on?
How long have you had the computer, what kind is it, did you just build it, what are the components inside?
details, details, details.
Hi, When i said CPU, i meen the central processing unit only, when i switch on, some times it goes upto windows and hang by itself. My cpu is Intel core i3, i am using a intel mb and 2GB ram. I build it myself. Is this because of PSU? or the hotsink?