I have the same CPU and cooler with a Biostar TA880GB+ mobo, and easily get 3.9Ghz. My X3 445 didn't have a working 4th core, but did have the 6MB L3 cache.
I think you need to increase your CPU-NB voltage. I believe stock is 1.1500V. I added +0.050 V offset to get things stable.
These are...