Does anyone fan randomly kick on?

[Nautilus007]

I am noticing while laying in my bed when my late 2012 iMac fans just go full blast for 15-2" seconds. The computer is idle and the display is asleep. Anyone else?

 

[Siderz]

Nope.

In fact, my iMac 2012 fan has been at ~1400rpm since the day I got it. I don't think I've seen it go up once.

Perhaps it went up to ~1600rpm while I was encoding a huge amount of videos, I can't remember.