Well, my son found that there is a program that can control the minimum speed of the fan(s) in a Mac, called smcFanControl
, and it does a decent job. If you speed them up, and then turn them down, they take a while to slow back down again. AFAICT, if the temps rise, then the speed ramps up -- this program lets you set the minimums.
For an amazing amount of temperature info, you can use Temperature Monitor
-- it reads a total of 13 different temps in my iMac; including things like the memory controller and wireless module, but also the stuff that is more important: heatsink and CPU core temps, GPU, external HD and SMART sensor. You name it, it is there.