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macrumors regular
Original poster
May 12, 2010

After having my iMac 2017 27" for 2 weeks already, it just started making some subtle rattling noise. At first it switched from being silent (only hearing the fan at 1200rpm) to the additional rattling sound (also with the fan at 1200rpm). Now I've this subtle rattling sound permanently in the background.
This is something you only hear if your room is completely silent but I'm afraid it may get worse over time.

Anybody else experienced this and knows where this is coming from? I assume it is a problem with the fan itself that it doesn't run as it should. Is there an app that allows me to control fan speed? would love to pause it for a moment.


macrumors G4
Jul 30, 2003
SMCFanControl allows you to adjust the fan speed. You can't actually pause, or turn OFF the fan, but you can increase the fan speed, which can also help you decide if the fan is the source of the noise.
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macrumors G3
Mar 29, 2008
Thanks! SMCFanControl did not work (nothing happened when I tried to change the rpm) but I have downloaded Macs Fan Control and it worked ( . I turned the fans all the way up and then down again and the rattling is now gone. I hope it will stay this way... :)

Fans can be funny things. I know my 2012 iMac needed a smack on the back every now and then to settle the fan rattles.


macrumors newbie
Aug 23, 2017
Noticed yesterday the same after bringing down brightness. It seems to come from lower left side.
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