While the Zalman would be the better choice, people don't give the large AMD stock cooler that comes with the PhIIX4s enough credit. The cooler has 4 heat pipes, a copper base, and decent TIM. Granted it is a bit noisier than one would like, but it does a more than adequate job cooling the 125W Phenom IIs. The last PhIIx4 956BE I had was easily able to reach 3.8GHZ with just the stock cooler/TIM on extended runs of Prime95. The temps never reached above 58C as recorded by Core Temp. I'm sure I could have taken the CPU speed even higher and still stay below the 65C threshold. But a well ventilated case is a must.