Could be many things.

Is this something that just started? Have you added or changed any software or hardware?

Are you sure you are virus and malware free? Lots of threads here on this subject.

Does this happen right when you turn the machine on or after it has been on a while? That could indicate a heat problem. If yes open up the case and blow a fan on it to see if it goes longer or the problem goes away. Could be time for a cleanup and possible fan replacement.