Recently my iMac started to emit a buzzing sound when I powered it up. Have tried SMC reset and NVPRAM reset as well but the sound doesn’t go away. Has anyone encountered this issue and any idea what is causing it? I had replaced the mechanical hard disk with a SSD and added another 8GB of RAM 3 years ago and it’s been working fine till now. Gave the air vents a good vacuum too as there had been some black debris being blown out.
iMac 27″, macOS 10.12
From what you have described, it sounds like you may have a failing fan.
One way to check the fans, is with MacFanControl from > https://crystalidea.com/macs-fan-control
First check the speed of each fan to see if it is running at the default speed.
Then slight increase the speed of each fan to see if the buzzing sound changes.
Hi,
I suppose fan is something wrong. You would need to replace it, though it could be possible fan dust makes buzz sound. Try to clean up the fan with air blower if it could solve your issue.
iMac 27” (late 2009 model) - Buzzing sound
