imac 2021 buzzing noise

When most of you hear the noise at low display brightness, it might be a trashy resistor. The power adapter of my razor also makes such a noise. And years ago there was such an issue with Intel notebooks, which was called cpu whining, when the processor decreased its clock frequency.

If that's the case with the iMac, I fear no software update can fix this. I hope this is not a thing, every of the new iMacs comes with. Mine will be delivered in two weeks.

I hope, Apple have a solution with this and replaces affected devices with ones without the problem.

Also it would be interesting, how old are the people, who hear it and how old are those, who doesn't. Young people are able to hear higher frequency noises than older people. Maybe that's why the Apple QA team missed that issue, if it comes with every device.

I just got mine replaced, and it is not doing the noticeable noise anymore. Though if you are in a perfectly silent room and really get your ear close to the chin, you'll hear a slightly changing noise when changing the brightness. Barely noticeable, but maybe that helps for your diagnostic.

It's true that some people will not notice the noise when its "loud", either because of the environment or hearing impairment...

I got my second unit and it has the same problem like the first one (and the rest of us here). If I lower the brightness below 70-80% the noise is coming up. I think the noise from the second unit is not so loud as the one from the first.

Same here! I had my unit replaced and the whining sound is still there, though not so loud as it was in my first iMac M1.

I'm pretty sure it's affecting ALL new iMacs: that's a shame! I hope Apple will solve this somehow!

It appears to be connected to power usage. Drawing more power seems to help eliminate the buzzing sound. When I connect my iPad to the iMac (via USB), the sound goes away as the iMac utilizes more power to charge the iPad.

I just wanted to thank you guys for the insight regarding the screen brightness. It's exactly what's going on with my iMac as well. And I just went to the Genius Bar today, dude had no hack of a clue. I just can't live with this noise. I'll contact Apple again.

Agreed, sharing our experiences has been helpful. And besides this buzzing noise issue the M1 iMac has been exceptional.

I have an open ticket with Apple and they are willing to exchange it but to be honest I'm holding off for now. From what I'm reading many others have tried to exchange theirs only to find the replacement has the same issue. I'm willing to go through that hassle if I'm confident Apple has determined the issue and new replacements consistently don't have the problem.

A part of me is worried that this will be viewed as expected behavior and won't be resolved with this generation of the iMac.

I've had my M1 iMac for a few days and I can confirm than mine whines too. I'm certain all do to some extent. It bothers me a little but I mostly notice at night, or if it's really quiet during the day but not always. Funnily, only certain brightness clicks triggers it. Maybe it doesn't whine at 7 clicks, then whines at 8, then stops at 9 for example. I can live with mine because I think it's a mild case. I can see for louder ones an exchange is necessary. But I also think it's useless to have it exchanged now if the whine is faint, because until Apple changes something it's very probable that a new will whine even worse. So better stick with good enough for now.

It could be what is known as "coil whine" which from what I'm reading is normal for electronics and the noise can get quieter over time or disappear altogether.

Two weeks in I do notice it less now—not sure if it did in fact get better or if I'm not as bothered by it. I also turned off "Adjust brightness Automatically" as I found myself not needing it with my desktop environment.

Yes it is coil whine. Intensity changes for every iMac. Let's say that there are Apple products with less to no coil whine, whereas in this case it seems to be affecting every iMac M1 out there, to different degrees. I can hear mine in a quiet room but mostly decide to ignore it. No point in having a new one as it could be worse.

There seems to be two issues in this thread that need separating out. The original is far more like coil whine, power/transistor related noise, but further down we're into the high-pitched whine from the display which goes away at full brightness. I've just started the return of my second iMac 2021 because of this high-pitched whine/display brightness issue which Apple Support still claim to know nothing about. Incidentally, as others have pointed out, not everyone can hear it as it's so high pitched, my wife can't unless she really gets close to the display and listens for it, but for me it's unusable.

I do hope they get to the bottom of it and fix it for a future batch, I may try again next August when the student deal is on again!

Some are more sensitive than others for sure. In your case yes I think you should just wait some months, or until they change something hardware wise.

Anyway I can hear "chirping" from the same spot and at 50-70cm distance also when performing some slightly intensive tasks, like when fast forwarding an HD video with the arrows, or when Lightroom previews different filters on the fly, in a quiet room.

I could live with that. I'll probably still return mine other reasons (speakers tuning mismatch) but that is another matter. It is unfortunate because you never know if the new one will have other problems (mine has a perfect screen for example). I really need this computer right now, my old ones is too slow for work and the new ones are around the corner so this is a very unfortunate timing for this to happen XD

Same here, it indeed gets louder when dimming the display. I heard from another user the sound should settle in a few days, I don't know if it's true though. I guess people don't wait for their computer to "settle" rather contact apple right away for a replacement. We'll see...

@Old Toad

May you talk about another iMac than the 2021 24"? Because the iMac which is discussed here, have no fan at its back. Fans are only on the bottom of the chassis.

I got mine some weeks ago and doesn't hear a noise (except the fans). But this may be because also I doesn't hear a sinus sound above 14,400 Hz (tested with Apps on iPhone and this iMac).

Just a quick update...

While the noise is clearly caused by dimming the screen brightness, I've also noticed that, if the display turns off after some moments of inactivity, the noise persists. It only ceases minutes later, when the computer goes to sleep.

But then again, screen brightness HAS to be low at the point where the screen turns off for the noise to be heard.