I find that my freezer Pro 7 is fine with quite fan turned on in the BIOS
And it's keeping my pentium D about 5 degrees cooler than the stock cooler
My one word of warning is that if you'er useing a rear case fan and a PSU that has a 120mm fan on the bottom, is that the Freezer pro 7 + zalman case fan combo can suck the air too well, it was giveing me problems as the PSU couldn't get enough air through it.
This would depend on your case layout and PSU.
I sorted out mine by moveing the zalman case fan to the front of my case to suck in air, the majority of the air the freezer pro 7 is moveing still goes out through the rear grill and the PSU is sucking out the rest.