Late 2015 retina iMac electrical buzzing

[Bruins3]

Hello, new to the forum. I have a late 2015 iMac:

4.0GHz quad-core Intel Core i7, Turbo Boost up to 4.2GHz
AMD Radeon R9 M395X with 4GB video memory

I noticed a faint electrical buzzing sound that intermittently comes from the bottom left corner of the screen. It happens sporadically, however one way I can reproduce it is by clicking the Downloads icon on the Dock which makes the noise when the icons fan out. I have tried connecting to different UPS units and different circuits and the noise persists. It is definitely not a fan noise, it is more of a high pitch electrical buzzing. Just wanted to see if anyone else has noticed this or if perhaps I have a defective unit. Thanks for any insight.

 

[desmond2046]

I have encountered similar buzzing with my Macbook Pro retina. I thought it was electric noise but it turned out to be the fan noise...
You could try smcFanControl to change the fan speed manually to completely rule out the possibility of the fan noise.

 

[Bruins3]

Thanks for your response. I tried changing the fan speeds and this sound seams to be different. Any one else having similar problems?