iMac Fan Goes Hyper-Speed

iMac Fan Goes Hyper-Speed

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Imac fan goes into hyper-speed.
Imac fan goes into hyper-speed after hard drive replacement.


If you’ve upgraded your iMac’s hard drive lately, or replaced it when it went bad, I bet you were surprised to find that after the install, the fan went into hyper-speed and never, ever stopped again.   Wheee.  That happened recently to client’s computer.  Their hard drive went bad, and we had to replace it.  After the repair all seemed good, but then a few days later the client called. and said the fan was too loud.  I dropped by the client’s business, and not only was the fan really loud, it spun at full speed every single moment, as if it were micmicking a the blades of helicopter about to take off.  I couldn’t figure out why until I researched it in depth on the internet.

Turns out there is either firmware in all Apple-configured hard drives or a heat sensor cord attached to one and if you replace it with an ordinary drive, the fan will go hyper.  iMacs before model 11,3 come with a heat sensor cord and when you replace your hard drive, you need to buy and install a heat sensor cord specific to the type of the new hard drive.  The cord goes from the hard drive to the motherboard.  It will regulate the fan.  Yet with the 11,3 and newer models, Apple stopped using the cords.  Oh no.  I thought I would have to tell the client, their fan would never, ever stop again. It had gone manic and too loud forever.


I found out that there is an answer, however.  You can get software that will regulate the fan  for you.  It is called SMC Fan Control. You can download it here from Cnet’s

So tomorrow I’m remoting into my client’s computer and installing it and getting that fan under contol.

Photo of iMac by  (Notice the cans of Tim Horton’s coffee behind the iMac.  This is obviously a Canadian iMac.)


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