Woah, my computer made the "shut down" noise

[Hugbees]

I was just in my room minding my own business and I heard my iMac "shut down" but nothing happened, and I'm still able to use it like normal as I type this message.

It seemed to quiet down my fans though, they are still running but much quieter so I guess in a way its a good thing.

I'm just curious as to what happened here.

 

[plumbingandtech]

I was just in my room minding my own business and I heard my iMac "shut down" but nothing happened, and I'm still able to use it like normal as I type this message.

It seemed to quiet down my fans though, they are still running but much quieter so I guess in a way its a good thing.

I'm just curious as to what happened here.

Was it the hard drive parking (shutting down to save energy).

Mine do that if I leave my mac alone for a while. Check your Settings -> Energy Save -> Put hard drives to sleep when Possible.

NOTE: I do not have that checked but my hard drive does it anyway so I think the firmware of the HD overides it in some cases.