My computer slows down

[Superrock]

If my computer been on for a long period of time it starts to slow down as if I'm running a ton of applications but I'm not. Resetting the computer fixes the problem. I did a clean format a few months ago and the problem is still present. Do I have a problem with my ram or motherboard? I used to try to OC my motherboard years ago but it was too unstable.

 

[mpilchfamily]

Please list your hardware.