iMac's fans make awful noise My iMac's fans are making an awful lot of noise, sounding like a piece of cardboard is in them. It's a kind of ticking noise. This is happening since a few months ago. I have not changed any hardware. I have never encountered any other problems with my iMac and it has never crashed. My Mac is running normally and fast.

Here is what iStat says:



I have an Intel iMac (iMac9,1), Intel Core 2 Duo @ 2.66 GHz, 2 GB RAM, running Mac OS X 10.6.6.

I have tried to reset the SMC but this did not help.

How can I make this noise go away without opening my iMac or sending it back to Apple?
Your fans are running at speeds appropriate for that model. Even using a stethoscope on the rear of an iMac, good techs have been confused between hard drive and blower noise unless you can change the noise by increasing or decreasing the fans or the HDD.

Rhythmic blower ticking is one of two things:


Failing or failed bearings in the blower.
Foreign object (paper, hair, other) lodged in the blower.


Choice #2 is less likely since the airflow around the unit usually precludes things getting stuck there. Also the design makes it unlikely things large enough to make noise or stick can enter the blower area.

I wouldn't recommend shaking an iMac (running or not), but tipping it on a side or upside down with a friend's help and then powering it on would let gravity and the airflow dislodge all but the most unlucky piece of debris from a blower. Be aware that succeeding to move debris may land such debris in a worse place than a blower, so do use caution. 

If the bearings are the cause - you might try a fan control software to run the fans faster (sometimes higher speeds are less noisy) but do get ready for a visit to the shop as bearings don't fix themselves and the noise will get worse as it wears. A technician is the best person to get debris out and truly resolve a ticking noise whether it's a hard drive, optical drive or a blower.