Flutter noise (from fan?) on startup (2020 27" iMac)

[neuralengine]

Had all the windows around the house open until a few days ago as it was still summer weather.

With the windows closed the noise floor in my office is much lower now and I noticed that my new 27" iMac does a weird little flutter as it spins up the fan upon waking from sleep or starting up from shutdown. It’s a really quiet sound but trying to think through why it would happen I can’t come up with anything good.

Running Apple Diagnostics shows no issue. Lifting the iMac and moving it around / tilting it I don’t hear anything loose there. Once the fan spins up, it’s very quiet at idle (quieter than typing softly on the Magic Keyboard) and doesn’t seem to have any issues when spinning up (e.g. when doing Cinebench.)

I have two days left on my return window and debating whether this is worth the hassle of returning and being without a computer for weeks. Having been burned with two lemon displays on a 2019 iMac, I also don’t particularly want to test fate in that regard as this display is very good.

Is this flutter noise cause for concern? Should I just live with it and have it serviced if it gets worse? It doesn’t affect normal use, just a little worried this might be the beginning of a bigger problem.

 

[EvilCo_E]

Mine does it as well, I don't think its an issue though, I've had other computers do similar things with their fans on startup. I believe its related to something akin to the fan controllers needing to load. I don't know much about the iMac's fan but I'm fairly sure its not a problem.

 

[KrazyKanuck]

I had two, and both made the same noise. I wan't worried about it. In your case, I would definitely not return the unit.

 

[bgab]

A momentary "squeak" is the best way I can describe it. Does that sound correct? Wasn't sure if it was the fan or power to the display.

 

[neuralengine]

Thanks everyone, sounds like I’m overthinking this one and it’s normal.

A momentary "squeak" is the best way I can describe it. Does that sound correct? Wasn't sure if it was the fan or power to the display.

It’s less of a squeak and more a rapid series of clicks. Like a cat purring or a small bird flapping its wings. I recorded it on a voice memo but the ambient noise (which in reality is almost non existent) and the iPhone mic’s hiss are near the same level as the noise I’m talking about. It lasts half a second maybe right as the fan goes from stopped to moving:

fan flutter - Clyp

Listen to fan flutter | Clyp is the easiest way to record, upload and share audio.

clyp.it

 

[bgab]

OK, I'm hearing something different then

I think I've heard what you posted on previous iMac's. I'll look out for it on mine, but like other replies, I wouldn't be too concerned.

It's not as if I haven't heard a display make a noise in the past either. Just very sensitive to new sounds I guess. Don't want to hijack, but would appreciate it if someone could advise on whether they are hearing it too.

 

[neuralengine]

OK, I'm hearing something different then

I think I've heard what you posted on previous iMac's. I'll look out for it on mine, but like other replies, I wouldn't be too concerned.

It's not as if I haven't heard a display make a noise in the past either. Just very sensitive to new sounds I guess. Don't want to hijack, but would appreciate it if someone could advise on whether they are hearing it too.

Yes I hear a very short, very quiet high pitched chirpy squeak right at the beginning of the waking sequence, a second or two before the fans even start spinning up. Does that sound right?

Sounds like electronics turning on to me.

 

[BuCkDoG]

I heard it in your video but I'm typing right now on the 2020 5k iMac and have not heard anything from sleep to waking up. Definetely not something worthy of a return personally.

 

[shhh2020]

Have that very short rattle as well. Fans spin up, then slow down again to the default 1200 rpm. Short clickety/rattle, but feels like regular behavior. Doesn't bother me though as much as the fan-noise/airflow-noise through the air vents on the back which is constantly there. Shouldn't the iMac be as silent as e.g. a MacBook Pro which actually isn't audible at all while simply browsing the web, etc…

 

[bgab]

@neuralengine Yes that’s the one! Thanks for confirming - nice to know there’s a degree of normality to both “issues”. For my part, I too can confirm the fan flutter at start/wake.

Given that we’re hearing the same thing, I’m somewhat satisfied that this will be OK in the long term. Apple Care if not, I guess. Better that than rolling the dice with a replacement.

For what it’s worth, I’ve never had a truly silent Mac, regardless of the form factor. That said, I haven’t had a new iMac in over a decade now! Loving this one despite these minor issues.

 

[neuralengine]

Have that very short rattle as well. Fans spin up, then slow down again to the default 1200 rpm. Short clickety/rattle, but feels like regular behavior. Doesn't bother me though as much as the fan-noise/airflow-noise through the air vents on the back which is constantly there. Shouldn't the iMac be as silent as e.g. a MacBook Pro which actually isn't audible at all while simply browsing the web, etc…

Yeah the fan noise at idle is noticeable in a quiet room. It’s definitely louder than a 13" MacBook Pro but much much quieter than older iMacs. Hopefully Apple Silicon ones will be quieter still. I think part of why these are louder than the laptops is that there’s just more room for the air to move around in.

Give it a few weeks, it might not bother you as much after a while. I did get used to my 2011’s idle airflow noise which I thought was quiet but now sounds like a steam train compared to this one.

@neuralengine Yes that’s the one! Thanks for confirming - nice to know there’s a degree of normality to both “issues”. For my part, I too can confirm the fan flutter at start/wake.

Given that we’re hearing the same thing, I’m somewhat satisfied that this will be OK in the long term. Apple Care if not, I guess. Better that than rolling the dice with a replacement.

For what it’s worth, I’ve never had a truly silent Mac, regardless of the form factor. That said, I haven’t had a new iMac in over a decade now! Loving this one despite these minor issues.

For sure, good to know they’re not isolated. It really is a great machine, despite some minor issues!

 

[marathonmilk]

So I bought one of these machines, and have exactly the same issue. I was so annoyed by it I got Apple to replace it. Just booted up the new one and it makes exactly the same rattle!! Must be common to these iMacs, although I’ve never heard it on one before.
I suppose I’ll just need to get used to it.

 

[arz]

I have the same fan sound on startup on my 27” 2020 base model. Good to know it is normal.

 

[CE3]

I've noticed a very faint "woosh" of the fan when waking from sleep, but no rattle or squeak.

 

[neuralengine]

So I bought one of these machines, and have exactly the same issue. I was so annoyed by it I got Apple to replace it. Just booted up the new one and it makes exactly the same rattle!! Must be common to these iMacs, although I’ve never heard it on one before.
I suppose I’ll just need to get used to it.

Yeah, I feel you. I’ve had quite a few of these “I suppose I’ll just need to get used to it” moments with this iMac, which is unusual for me with Apple stuff and quite annoying given how much these things cost, but it’s still an awesome computer in the end.

 

[marathonmilk]

Yeah, I feel you. I’ve had quite a few of these “I suppose I’ll just need to get used to it” moments with this iMac, which is unusual for me with Apple stuff and quite annoying given how much these things cost, but it’s still an awesome computer in the end.

Yeah it’s a fantastic machine. I’m used to Apple products being completely uncompromising though, and a fan rattle doesn’t seem right in a computer of this quality (and price).

 

[marathonmilk]

Quick update: I spoke to Apple about the issue on my replacement, apparently there have been several reports of this fan flutter sound. They confirmed it was nothing to worry about, although I ask them to note I had raised it, just in case of any future fan failure.

 

[neuralengine]

Quick update: I spoke to Apple about the issue on my replacement, apparently there have been several reports of this fan flutter sound. They confirmed it was nothing to worry about, although I ask them to note I had raised it, just in case of any future fan failure.

Well, that’s reassuring! I still think this fan sounds a bit… weird but guess I’ll get used to it.

Surprised (pleasantly) that you got this response from Apple, anytime I’ve called them with issues I know other people were having they acted like it was the first they heard of it.

 

[neuralengine]

Quick update: I spoke to Apple about the issue on my replacement, apparently there have been several reports of this fan flutter sound. They confirmed it was nothing to worry about, although I ask them to note I had raised it, just in case of any future fan failure.

By the way, can you hear a very faint rattle on the right hand side of the computer during normal use? When the computer is on and the fan is idling? I’m talking really, really quiet. Sounds a little like a mechanical hard drive seeking, but maybe at 5% of the volume.

It bothers me but, doing a sanity check, I don’t think most people would notice something this quiet and it’s unlikely, for example, that I would even be able to convince a genius at an Apple store that it’s there.

 

[neuralengine]

So this is interesting, I am now getting this notice in the TG Pro app.

Apple Diagnostics still shows no issue.

 

[Mac_Ming]

By the way, can you hear a very faint rattle on the right hand side of the computer during normal use? When the computer is on and the fan is idling? I’m talking really, really quiet. Sounds a little like a mechanical hard drive seeking, but maybe at 5% of the volume.

It bothers me but, doing a sanity check, I don’t think most people would notice something this quiet and it’s unlikely, for example, that I would even be able to convince a genius at an Apple store that it’s there.

I bought my iMac2020 and was delivered a month ago and had the same annoying and distracting fluttering noise during idle time. It was gone after logging into the safe mode and then back to the normal mode. I am not sure if this was really the way to solve the problem because I can't test it right now. If any one of you has the same issue, you may want to try and see if it works. I hope it works! Here was what I did.

1. Shut down your computer
2. Restart your Mac
3. Hold down the Shift key
4. Let go of the key when the login window appears
5. You’re in the Safe mode — use any program for a minute or two
6. Restart your Mac in a normal way

 

[haddy]

Had all the windows around the house open until a few days ago as it was still summer weather.

With the windows closed the noise floor in my office is much lower now and I noticed that my new 27" iMac does a weird little flutter as it spins up the fan upon waking from sleep or starting up from shutdown. It’s a really quiet sound but trying to think through why it would happen I can’t come up with anything good.

Running Apple Diagnostics shows no issue. Lifting the iMac and moving it around / tilting it I don’t hear anything loose there. Once the fan spins up, it’s very quiet at idle (quieter than typing softly on the Magic Keyboard) and doesn’t seem to have any issues when spinning up (e.g. when doing Cinebench.)

I have two days left on my return window and debating whether this is worth the hassle of returning and being without a computer for weeks. Having been burned with two lemon displays on a 2019 iMac, I also don’t particularly want to test fate in that regard as this display is very good.

Is this flutter noise cause for concern? Should I just live with it and have it serviced if it gets worse? It doesn’t affect normal use, just a little worried this might be the beginning of a bigger problem.

Yes I have the same at startup, 2020 BTO maxed out iMac. Of no worry to me. Just love this machine

 

[Fishrrman]

"Yes I hear a very short, very quiet high pitched chirpy squeak right at the beginning of the waking sequence"

Sounds like a "dry bearing" making noise as the fan starts from 0rpm to whatever speed it's going to reach...

 

[LadyNinja]

Cant belive I just NOW, are seeing this thread. I didnt get many replys in my search from others.

First imac was with a nano screen. No fan problems. Returned because of the screen.

Second machine had a fan noise when startup, at the loading screen. They took it it for a fan replacement. Was not happy when the sale person told me they couldn't hear the noise.... The technician said it needed replacement, the sale person said they replaced it from good will.... I had a good audio file with the problem.

Came back, and now the sound under startup was gone, but it had it at idle, just surfing or doing nothing at all. I placed my ear at the back, and could hear the fan, like it was touching something, and I experienced that the sound could come on/off randomly.

The closest i came to figuring out of this issue, was from a macbook user on youtube. In the comments the solution was to hit the machine couple of times. It was quit the few with the same experience.

At this time, the sound on my machine was low. I took several smc resets (remember theres different methods for t2 chip - i tried them both, several times). At this point I felt mentally crazy. And tried for the sake of God not to think about it. After time went by, the sound disappeared, or at least I think so! Im not going to put my head close there again! before I could hear the issue from an arm distance. After several smc resets it was quieter, but still there. Have not heard it afterwards.
Im in a happy place now, without anxiety 😂

I contacted apple (not from my shop/country) they said I should send it into repair. Contacted my shop just to inform about the problem, in case it later comes back. They said I could bring it in.
For now im just going to monitor it. But having problems with the screen separating in the middle with true tone on-off on either sides. Waiting for an big sur update, if not I will send it in.


I has been alot of pain with the experience of the imac 2020. We had also the screen glitch. I have never ever considered an pc, but I was sooo close to get rid of this imac. Our 2012 has run smooth since day one! Come on! Im also having issues with adobe programs, lightroom and photoshop. Sloooowly getting better. Had some big glitches when adjusting the images, whole system sirup slow and or/ the program. Afterwards im afraid of updating. Cant see it will get the best either, with the silicones on the way. I can see myself switching the machine in a year or two. This time the whole mac experience just killed my soul.

 

[neuralengine]

Cant belive I just NOW, are seeing this thread. I didnt get many replys in my search from others.

First imac was with a nano screen. No fan problems. Returned because of the screen.

Second machine had a fan noise when startup, at the loading screen. They took it it for a fan replacement. Was not happy when the sale person told me they couldn't hear the noise.... The technician said it needed replacement, the sale person said they replaced it from good will.... I had a good audio file with the problem.

Came back, and now the sound under startup was gone, but it had it at idle, just surfing or doing nothing at all. I placed my ear at the back, and could hear the fan, like it was touching something, and I experienced that the sound could come on/off randomly.

The closest i came to figuring out of this issue, was from a macbook user on youtube. In the comments the solution was to hit the machine couple of times. It was quit the few with the same experience.

At this time, the sound on my machine was low. I took several smc resets (remember theres different methods for t2 chip - i tried them both, several times). At this point I felt mentally crazy. And tried for the sake of God not to think about it. After time went by, the sound disappeared, or at least I think so! Im not going to put my head close there again! before I could hear the issue from an arm distance. After several smc resets it was quieter, but still there. Have not heard it afterwards.
Im in a happy place now, without anxiety 😂

I contacted apple (not from my shop/country) they said I should send it into repair. Contacted my shop just to inform about the problem, in case it later comes back. They said I could bring it in.
For now im just going to monitor it. But having problems with the screen separating in the middle with true tone on-off on either sides. Waiting for an big sur update, if not I will send it in.


I has been alot of pain with the experience of the imac 2020. We had also the screen glitch. I have never ever considered an pc, but I was sooo close to get rid of this imac. Our 2012 has run smooth since day one! Come on! Im also having issues with adobe programs, lightroom and photoshop. Sloooowly getting better. Had some big glitches when adjusting the images, whole system sirup slow and or/ the program. Afterwards im afraid of updating. Cant see it will get the best either, with the silicones on the way. I can see myself switching the machine in a year or two. This time the whole mac experience just killed my soul.

Very sorry to hear about your experience. I think a significant portion of these iMacs have unacceptable quality control issues.

I hope that this is a temporary lapse. The pandemic likely prevents Apple from having enough staff on things like these and also keeps them from doing the kind of hands on, in person quality control they usually do over in China. And, at the same time, I don’t think Intel Macs are their focus any more.

I’ve made peace with the fact that I’ll probably replace this one with an M1 Mac within the next two years - but keeping it for only two years makes it a lot more expensive in the long run. My 2011 lasted me nine years without any issues, like your 2012.