I have an AMD Phenom II x64 965 processor and in task manager it shows it running at .79 Ghz. WHY?! My frame rate in games sucks and I am getting very frustrated.

I have an AMD Phenom II x64 965 3.4 GHz processor but in task manager it shows it running at .79 Ghz.  WHY?!  My frame rate in games sucks and I am getting very frustrated.