It would tell me either you have a virus, a bit of server software running.
Or a cpu/ Gpu bitcoin or crypt o mining software running as a back ground task in windows.
The first thing to check is what is running or launching after windows has loaded.
In your search box of windows type: Msconfig.
Click on the startup tab in the box that opens.
And look for any bit of software, task or process that is ticked and auto running.
Untick any reference to any bit of software ect.
With an obscure name other than you know what software is set to launch after windows has loaded.
Run both an antivirus scan, and a malware scan of your system.
The fact that the cpu cools off, when you log off tells you it is a task or process running or set to launch on your windows os the first time the system is powered on and windows is loaded.
Logging off terminates any tasks or processes running in windows for the set user.