It sounds like a heat issues to me ! I would power it down and take the side off of it and blow it out good with a can of computer Air. You can pick them up anywhere. Computers are Natural dust boxes! Every 3 to 6 months you should blow it all out and inspect your components, Looking for anything restrictive. Check your fans make sure they all are pulling good. That would be the first thing i would do if i were you.

Gl