I would suggest either the Alpha PAL6035 or the new ThermalEngine HS.
Both should be fine for the CUSL2 (I use the same MB, and an Alpha PAL6035)
The Alpha got me from 45-50C down to 39-40C at full CPU load. Keep in mind I live in Southern California so the ambient temp is 27-28C to start with, making everything that much hotter all around.
I have heard that the ThermalEngine is even BETTER than the PAL6035, but I have yet to try it. Looking at the design, it looks like a superior HS. Slotting the bottom of the HS not only increases surface area, but it allows more airflow to the PCB of the FC-PGA processor.
Either of these HS can be paired with a 38cfm 60mm fan. I suggest the Delta Black Lable if you can stand the noise this 7000RPM fan creates.
Joshua
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The best things to come out of Berkeley was LSD and UNIX. Coincidence? I think not!