27" iMac fans on full

After moving an iMac, i switched it on to find that its fans were blowing full blast, making quite a noise.

I tried:

• switching it off and back on
• restarting it
• reseting pram
• switching off, leaving it a while and switching back on again

none of these worked. I came across this article in apple knowledge base. reseting smc worked a charm.

Basically switch off, unplug for 15 secs, plug back in. Done