High pitched whining noise persisted through 3 replacement 2021 iMacs

Hi everyone,

Just wanted to log my experience with this here to help anyone going through the same issue.

Those of us with good ears and a new 2021 iMac are very likely to have noticed an incessant mosquito-like coil whining noise, most prominent when you place your ear near the power cord socket on the back of the computer.

Things that affect it seem weird:

• lowering the brightness to around 70% triggers the noise, whereas having it at blinding light silences it. Each notch of brightness below that changes the frequency and movement of the sound slightly.
• moving the power cable slightly and holding it to the side seems to also stop the noise, but it continues when you let go

I've just had my THIRD replacement iMac delivered, with my now hopeless predictions confirmed as it made the exact same noise as soon as I touched the power on button.

I've tried different rooms and plugs with no variation.

I am going insane and now even starting to create the noise in my head when trying to sleep!

My boyfriend can't hear such high pitched sounds but even he heard it when he put his ear close and I toggled between the brightness to show him.

I've seen other posts about this online but no one who'd been successfully helped!

After days and days spent transferring data from faulty iMac to faulty iMac (I always had to keep the new one and send back the previous, even though it wasn't fixed), talking to the support team with the same information and apparent unawareness of the issue being repeated to me, I've finally had some kind of reasonable offer made.

After eventually getting through to the technical team and speaking to somebody who acknowledged this as an issue on their end and not brushing it off, I've been offered the semi-magical third option (the first two being another replacement, or a refund, leaving me with no computer and all my life's work on a hard drive, after already sending them my old working iMac for a trade-in)...

So they are letting me keep the third one, but have promised that if they fix this issue in future and bring out newer models, I am guaranteed to have someone attempt to fix my current computer with this new info, OR if that fails, get a replacement with a new model.

This was enough for me, as the trauma of it was having spent £2k on something I wanted to last me 10 years like my last one, so at least now I know I'm being taken seriously and that I will hopefully have an improved model for that money at some point in the near future.

I know this still isn't a fix, but I at least wanted to properly acknowledge this on the forums here so others don't think they're going crazy!