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My iMac system fan will not stop


macrumors newbie
Original poster
Sep 2, 2012
Cardiff S.Wales
Can anyone help as my iMac system fan will not stop and is coming on as soon as I switch the mac on I have done a SMC reset and also a PRAM and NVRAM reset but this dose not do anything also the mac slows down considerable and when it eventually starts up all the apps when I click on them bounce and tacks forever to load up.


macrumors 6502a
Jun 24, 2012
The minimum speed of the fan is about 1200 rpm.

It will never be off when the machine is running. If it ever stops then *immediately* shut the machine down and take it in for service. At no point with the system powered up should the fan stop.

If the machine is slowing down and showing poor performance then check to see that your startup disk isn't full, and if it has plenty of free space then a sluggish performance problem suggests the hard drive might be failing.
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