I have a Pentium 4, 2.4 GHz CPU, Socket 478. I want to replace my Fan, for the 2nd time, with a still quieter one— What is the minimum &/or recommended CFM[cubic feet per minute]I need? I don’t play video games or watch movies or anything I believe is CPU intensive. I ask the minimum CFM because: the less air volume, the quieter the fan tends to be. ---- 1]The current Fan is 20 CFM , 36.5 dB, 60 x15 mm. The heat sink is 60mm x 60mm x 35mm w 42 fins of skived aluminum. 2]The original Fan was 24.4 CFM , 40 dBA [& heat sink ] by Dynatron.

I think you'd be better looking at stated manufacturer's specs as regards the dB ratings for fans rather than going by airflow - the way they are manufactured tends to be more important than airflow figures because you may have a massive airflow over aluminium tines comparing to a smaller flow over copper tines both producing the same cooling. Look for fans rated for your CPU & then compare the dB figures. "I know that I'm mad - I've always been mad..."