iMac Making Buzzing Noise

Marc

Marc

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My iMac keeps making a strangle buzzing noise. I've made a recording using my phone but don't know how to share it here.

It's a 2017 model but I bought it in 2019. It's running Big Sur 11.2.1
 
I’m by no means any kind of IT person but it sounds very much like a few external hdd’s that I’ve had just before they failed
 
Hadron said:
I’m by no means any kind of IT person but it sounds very much like a few external hdd’s that I’ve had just before they failed
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Oh I hope not. I've got 2 and neither are that old.

Interestingly, the buzzing stopped when I moved the Mac just a little although it started again a couple of minutes later.
 
Does it have external speakers?
It sounded a bit like mains interference being picked up by your audio system.
 
I don't think it's mains interference. The mains here in the UK cycle at 50 Hz. This was much slower than 50 Hz, IMO. It definitely sounds like mechanical noise to me. As it's an iMac, you could possibly identify whereabouts in the unit the noise is coming from. And if you compare it to a diagram of the innards, you might identify what is. Seems to me to most likely be a failing drive, and moving the Mac would make the noise change until it settled again. Having said this, most of the drives I've had fail have made a loud clicking noise first, so I could be wrong.

EDIT
Spoke too soon. I loaded it into Logic Pro, normalised it and put an EQ across it. It's peaking at 100 Hz, twice the rate of mains hum. And the waveform is most similar to a sawtooth wave rather than a mains-hum square wave. In the old days, some bits of failing electronics might make a similar sound - valves, maybe, or an old CRT tube. But my money (well, 50p) is on a failing drive. Would love to be proven wrong, though.
 
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garryknight said:
I don't think it's mains interference. The mains here in the UK cycle at 50 Hz. This was much slower than 50 Hz, IMO. It definitely sounds like mechanical noise to me. As it's an iMac, you could possibly identify whereabouts in the unit the noise is coming from. And if you compare it to a diagram of the innards, you might identify what is. Seems to me to most likely be a failing drive, and moving the Mac would make the noise change until it settled again. Having said this, most of the drives I've had fail have made a loud clicking noise first, so I could be wrong.

EDIT
Spoke too soon. I loaded it into Logic Pro, normalised it and put an EQ across it. It's peaking at 100 Hz, twice the rate of mains hum. And the waveform is most similar to a sawtooth wave rather than a mains-hum square wave. In the old days, some bits of failing electronics might make a similar sound - valves, maybe, or an old CRT tube. But my money (well, 50p) is on a failing drive. Would love to be proven wrong, though.
Click to expand...

Thanks Garry

Didn't understand 90% of it but I think I'll get another hard drive.
 
Marc said:
Thanks Garry

Didn't understand 90% of it but I think I'll get another hard drive.
Click to expand...
You can run the Mac off an external hard drive. I run mine off an external SSD. Replacing the internal hard drive on my 2012 iMac is a right pain as the screen is glued in and needs to be removed to access the hard drive. I think it’s the same for all macs from 2012 onwards.
 
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rob-nikon said:
You can run the Mac off an external hard drive. I run mine off an external SSD. Replacing the internal hard drive on my 2012 iMac is a right as the screen is glued in and needs to be removed to access the hard drive. I think it’s the same for all macs from 2012 onwards.
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Yes the display becomes all-in-one from 2012 and is held onto the chassis by adhesive foam strips, (they can be removed and replaced).
It's not a major job to replace the drive but it is fiddly and has the potential for damage if you aren't very careful:-

How To Here
 
I was rather hoping it would be an external drive that needs replacing, the internal one shouldn't fail after less than 2 years, surely!
 
Marc said:
I was rather hoping it would be an external drive that needs replacing, the internal one shouldn't fail after less than 2 years, surely!
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Surely you should unplug the external drives - if it stops buzzing it's one of them
 
davidy233 said:
Surely you should unplug the external drives - if it stops buzzing it's one of them
Click to expand...

Except that the iMac stops buzzing if I move it which I'd have to do to unplug the drives.

It's actually been silent so far today
 
IF you've got space to move the thing so you can unplug the drives, do so so that when it starts buzzing again, you can get at the plugs.

If it's a 50 Hz (or harmonic thereof) hum, I'd definitely be thinking mains hum of some sort. Possibly an LED light, especially if there's a dimmer in the circuit.
 
Nod said:
IF you've got space to move the thing so you can unplug the drives, do so so that when it starts buzzing again, you can get at the plugs.
Click to expand...

I'd still have to touch it to remove the drives
 
Could be failing:

- Speaker(s)
- HDD
- Fan (bearings or other)
- Vibrations from the PC or something external
- Could be peripherals plugged in and the noise is electrical interference. This happens when I plug in some items on my laptop on the left side only. It sounds similar but can also sound like some flickering electricity. The port still works but when I plug in HDDs or memory card readers in that one USB port they keep ejecting and reconnecting mainly when I try to transfer files. I only use the ports on the other side now. It's been like this for years and still working fine.
- Could be the plug socket. Maybe try it in a different plug.
- Could also be cable that have slightly been pulled out but are in enough to work so check they're all plugged in.

Hope you get it sorted.
 
Marc said:
Except that the iMac stops buzzing if I move it which I'd have to do to unplug the drives.

It's actually been silent so far today
Click to expand...
Ok and leave them unplugged for a period of time (hours, days, weeks) to see if they are the problem - it won't come back if they are
 
Are you sure that it's not one of the external drives causing the buzzing by touching another hard surface?
 
gramps said:
Are you sure that it's not one of the external drives causing the buzzing by touching another hard surface?
Click to expand...

I did think of that but the buzzing stopped temporarily when I touched the mac, the drives hadn't moved.
 
My experience with hardware and mysterious buzzing is to look at things that move. The component l have most associated with buzzing are fans, doesn't mean that they are failing but could mean that they have come slightly dislodged and are touching something like a cable or even that they have accumulated some fluff.
 
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