Neither will say how good a fan is....but the RPM is the spec you should look at when considering fans.Originally Posted by emoners
A 3000RPM fan is a 3000RPM fan and a 2000RPM fan is a 2000RPM fan and a 1000RPM fan is a 1000RPM fan. That is, someone who wants the cooling performance of a fast fan won't simultaneously get the noise profile of a low speed fan.
There's maybe 10-15% wiggle room between good fans and bad fans. That is, a good fan might move 10-15% more air at comparable noise levels than 'meh' fans or be 10-15% quieter with the same amount of airflow. Granted, there are also some really bad fans that are just abysmal and should be avoided like the plague.
Of all the stats, I do feel static pressure and dBA are the two least useful stats on a spec sheet (other than maybe designed power). dBA has little consistency from fan to fan or manu to manu (for instance, many implement different background noise reduction algorithms....that's how they get the single digit numbers on some fans).
Me saying static pressure will probably have a lot of people saying "blasphemy!" but hear me out. I'll agree that other than RPM, it's probably the easiest to consistently measure across manufacturers (based on Martin's rig he put together without much issue). But the way it scales (proportional to the square of RPM), is deceiving to most observers (a 3000RPM fan has 2.25x the static pressure of a 2000RPM fan, but moves only 1.5x the amount of air). Also, it's the opposite end of the P-Q curve of CFM, the end we're least interested in. If we had the entire P-Q curve of fans, the upper 20-30% is what we care about most, and the fans that have the best static pressure stats might not have the best airflow at a given restriction on the opposite end of the curve--ESPECIALLY when noise is taken into account.
I tested the 1000RPM variant in my fan filter comparison....it was horrible for anything other than open air.
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