|Simple answer is you can turn it off and save energy. |
Run performance monitor to log and see what is going on.
I suspect one of two issues. Hardware such as power supply or temp issue, the other being some software issue. Memory problem, program problem to even hacker attack.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10