iMac making a constant humming noise???

I had this happen to my 27 iMac about a year ago. It randomly started making a rather noisy (not extremely loud, but fairly noticeable) sound while I was using it one night. The next day, I woke it from sleep and it continued making the noise, I called Apple Care and she walked me throughout the "standard" procedures. Honestly, nothing she said fixed it.

Here is what I think it was.. Possibly a spider or small bug crawled inside and got logged somewhere in the fan and thus, created the noise I heard.

While this may sound outrageous to some, this actually happens more often than one would think. Talking to Apple Care on a follow up call, they told me that this is possible and they have heard of it happening quite often.

Let me know if this is still happening after a week or so, thanks!

 

Can be vibrations going down the stand/foot of the iMac to the table/desk, I had the same issue, so I put some sort of rubber carpet underneath the stand/foot.
Lifting the stand/foot slightly from the table makes the noise stop.
Happens when one don't have a real solid wooden table/desk.

 

That is strange, cause I as well used a 2010 and a 2011 iMac on the same table and got the same noise from both of the machines.

And you're welcome

 

mine makes a light humming noise from the hard drive but it is not very loud at all.