Upgraded to Sierra on my nMP, fan keeps running on top RPMs during 2% system load – blowing out room temperature air. SMC reset did not help – "jet engine" mode activates on reboot no matter how many times I did it. Also latest OS beta didn't help either. What's funny, system ran normally for a couple of days after I've killed and disabled photo indexing bullcrap. Using Macs Fan Control helps to slow it down, but system becomes sluggish (really noticeable in 3D games for example), like it's trying to throttle CPU because it thinks it's overheating (it is not, all sensors read 30-40º C, except from "PCIe switch diode" which reads around 60-70º C which is supposed to be normal). Did Apple screwed something up? Again. Update: AD said "there may be an issue with SMC", code PFM006 – I call bullcrap, it's too much a coincidence for it to happen exactly timed to major OS upgrade. Considering I'm not the only one having this issue.