Sure, I thought you said you built the tower though. On the upper half of the motherboard usually to the left of your RAM, sits your CPU fan/heatsink. You need to remove it, clean off your CPU and the heatsink surface (I believe Isopropyl alcohol is recommended here), reapply a dab of thermal paste to your CPU, and reset the heatsink onto your processor and reapply the fan
Ah; I did build it. For some reason, when you said "reset" CPU cooler, it sounded to me like you wanted me to reset software or settings rather than physically "re-setting" it onto the CPU itself.
Thanks, I appreciate your answer, as well as Timop's. I'm going to go ahead and order some new thermal paste today.