Are you still using the stock heatsink/fan that came with your processor?
Stock fans get the job done, but not much else. An aftermarket heatsink/fan for your CPU will allow for enhanced cooling, which can translate to improved performance if you take advantage of the overclocking headroom it provides. If you're not into overclocking, you'll still be amazed at just how much quieter your PC can become by swapping out that stock fan for something like the Zalman CNPS5X.
The Zalman CNPS5X is an affordable and reasonably sized aftermarket cooler that is aimed at the mid-level builder. It features copper heat pipes and aluminum fins, a mounting solution that does NOT require you to remove your motherboard (joy!), and a 92mm hydraulic bearing PWM fan.