2017 iMac BUZZ NOISE - URGENT

Hi,
I bought an iMac 27" 5k (2017 model of course) and I received it 10 days ago.
Since 3-4 days ago I noticed after just some minutes it makes a kind of "electric noise" when the monitor is "used", I mean when I do something on the screen, even for simple tasks: scrolling, resize a folder, watching video etc. Especially when the brightness is at max level.
I am not talking about fan, I talk about the electric buzz you can hear in the video I made.
This noise is NOT loud, but it's possible to hear it, I can't work well with it and especially I think it may become a huge problem near the future.

My questions are:
- Is it normal? does your iMac doing the same electric noise when you do something on the screen and brightness at max level?
- WHAT SHOULD I DO? I received it 10 days ago. Should I ask for a complete refund to Apple, and buy a new one?

Please check the video: of course I increased the audio so you can hear the buzz.

How did you make the recording? I can't tell for sure if there is a problem or if this is the kind of background noise that can occur in any situation where you are trying to record somewhat quiet sounds.

If you are concerned remember that you have 14 days to make a return. Once you get beyond that point you have at least a one year warranty (longer if AppleCare is purchased).

Slydude said:

How did you make the recording? I can't tell for sure if there is a problem or if this is the kind of background noise that can occur in any situation where you are trying to record somewhat quiet sounds.

If you are concerned remember that you have 14 days to make a return. Once you get beyond that point you have at least a one year warranty (longer if AppleCare is purchased).

Click to expand...

It's a recording made with an external professional microphone, on an external recorder, in a kind of recording studio. What your hear in the recording is 97-98% just the noise made from the computer.

After I made my post I listened to the recording again and heard the hum that you are concerned about. There is some background noise, as I would expect in all but the quietest situations, but the hum is there. This is not common. I certainly don't hear it on my 2015 iMac.

This is kind of a shot in the dark but is there anything thing nearby that could be causing some interference? Perhaps there is something plugged in nearby on the same circuit? If not I'd say it's time to get this checked out.