Hello,
I have new iMac M1. Today I've noticed there is an electrical noise coming from iMac. First I thought it was coming from fans but no. When I lower the brightness, this noise starting. There is no noise when using highest brightness level but when you lower more then 3 times from the keyboard, it stars again. Any solutions?
iMac 24″, macOS 12.2
If the computer was purchased direct from Apple then call AppleCare ( AppleCare contact Information ) to arrange an exchange. You have 14 days to do that. If you bought it from a reseller contact them ASAP to see if they will exchange, when you buy from a reseller you have to work within their sales policies.
It drives me bananas in a quiet room. It's been reported before unfortunately.
https://discussions.apple.com/thread/252979281
https://discussions.apple.com/thread/252793951
For me it's exactly as how others describe it. My guess is it has to do with PWM (Pulse Width Modulation) with regards to how the LED's of the display are dimmed. https://en.wikipedia.org/wiki/Pulse-width_modulation
There's a chance it'll fade over time or get louder, depending how Apple engineered the dimming circuit.
If you search back there are reports from 15 years ago about macbooks doing the same thing.
https://discussions.apple.com/thread/753424?answerId=3743196022#3743196022
Unfortunately it's kind of unavoidable unless Apple figures out another way to dim LED's. I guess it's good we're not listening to the CRT coil whine from fanless iMacs back in the day.
Looks like a hardware issue. I would schedule a bring-in repair appointment with Apple https://getsupport.apple.com/ and ask Apple to replace with new. Good luck!
iMac electrical noise from display
