Why is it that I can't ever get a Mac to spin up fans as the load on the CPU goes up? My 8 month old, bought brand new, 27" i5 iMac has no fan spin up even under heavy load. I've reset the SMC on this new iMac, have no 3rd party "fan control" software running at all, and yet the CPU fan sits there at 939 RPM (according to istat menus) while ffmpg is converting a video and has all 4 cores pegged at 391% and the CPU temp is up to 66 degrees celsius when sitting idle it's at 35-39 degrees or so. While yes, I could install 3rd party fan control software, why should I have to? Why shouldn't this iMac regulate it's fans right out of the box?