I have a Phenom II X4 955 @ 3.8GHz. I put a Coolermaster V8 on it and the idle temp is 43C! what gives?

I have nothing running in the background except for explorer.exe. I used the rubber washers that came in the package and securely tightened the cooler on the CPU. It is positioned to take in air from the intake fans and exhale air to the exhuast fans in accordance with my Antec 1200. I even used Arctic Silver 5 thermal paste. Why are the temps so high?