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How can you reduce the minimum fan speed?
I couldn't find any command line utilities for doing it with a quick search. There must be some though?
Neither smcFanControl or Fan Control are able to set the fan speed below 2000 RPM on my (Mid 2009, Core 2 Duo) MacBook Pro:
Why can't I set my minimum fan speed to 0 rpm?
smcFanControl only lets you set the fan speed in the range of Apple's min and max values. Setting it to zero is possible from the technical perspective but could probably damage your machine.
But would reducing the base speed to say 1000 RPM be harmful? And no, it isn't that loud even now, but the perceived level of noise seems to have a roughly exponential correlation with the RPM.
How low is very low? SpeedFan's FAQ also mentions the problem with reporting the speed correctly with low voltages. How can you find out the operating voltage, besides using an oscilloscope?
– Lri – 2011-03-22T14:34:17.853@Lri Actually, I used just a multimeter for voltage. Low depends on fan's rated voltage. Popular voltages are 5 V and 12 V. From what I've seen, 12 V fans won't start at around 5 V to 6 V, but that depends on the fan itself. I didn't have any 5 V fan to test. They are more common in laptops, so it could happen that your computer has one. As for reporting voltage, you'd need to disassemble the fan and see the Hall effect sensor. If you can read its markings, a simple Internet search will probably turn up its datasheet which will contain operating voltages. – AndrejaKo – 2011-03-22T16:41:35.777
@Lri Since you have a laptop, the fan assembly is very likely going to be small and it could be very difficult to read the writing on the sensor, if there is any at all. – AndrejaKo – 2011-03-22T16:42:45.683
I'll accept this as an answer for the is it safe part. Still looking for ways to drop the RPM though. :) – Lri – 2011-04-03T23:57:08.333