Zalman CNPS7000C horrible cooling

Hey community,

I recently bought a Zalman CNPS7000C-AlCu cooler from Fry's and installed it on to my aging Athlon x2 4600+ expecting better cooling than the stock AMD fan, but I was mistaken. The processor runs very hot with this fan at full blast and usually idles around 47-49C. At load, it doesnt usually get past 54C or so, which is not that bad, but I would like it to run cooler than if it had the stock fan on it. Here are the specs of my system.

-Athlon 64 X2 4600+ @2.4GHz
-Asus A8MZN-LA
-8800GTX 768MB
-WD Caviar 320GB
-Dynex 520W PSU
-Wintec AMP-X 800MHz RAM (4GB)
-WinVista 32-bit
-CM Elite 343

The case has a 120mm in the front and an 80 in the rear. Any help is appreciated.