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Mac mini constant buzzing sound (even when off)

A

Ascn

macrumors member
Original poster
May 10, 2020
48
25
Hi there, I just bought a new Mac mini, and I really like it.
But I have a problem: There is a constant magnetic humming sound when the device is on. You can clearly hear it when you put the ear to the device. It is constant and also appears when the device is turned off.
Is this normal?
 
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Ascn said:
Hi there, I just bought a new Mac mini, and I really like it.
But I have a problem: There is a constant magnetic humming sound when the device is on. You can clearly hear it when you put the ear to the device. It is constant and also appears when the device is turned off.
Is this normal?
Click to expand...
The power supply has a transformer and chokes, and they should hum when operating. Strange if they don't. Energy conversion is going on, hence the hum from the coils or choke. The only question is how strong it is. The hum should not be audible unless you put your ear close to the computer. The transformer winding is not primed properly in the built-in power supply. It may be humming from a poor quality power supply.
If you can hear it freely without bringing the computer close to your ear, then take it back to the store under warranty - coil or choke defect. Otherwise, the low-frequency sound may increase in the future, clicks and vibration may appear.
If you have electronics repair skills and no fear of breaking the thing, you can take it apart, and rewire the transformer winding yourself.
But if the humming is accompanied by whistling, then do not hesitate to take it back under warranty - evidence of faulty elements.
 
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OP:

Do you have grounded (3-prong outlets, such as in the USA/Canada) where you are?

Or... just 2 prongs?
 
I do not have grounding, I am from the EU, Austria.
 
"I do not have grounding, I am from the EU, Austria."

I'm guess that the lack of grounding is where the "buzz" is coming from.
Do you have any way possible to install a grounded connection?
 
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Ascn said:
I do not have grounding, I am from the EU, Austria.
Click to expand...
Yes you do… 🙄 Note: All Australian power points must be earthed to comply with the Australian Standards.
IMG_1951.jpeg
 
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IF it is actually a grounding problem, I've come across the following suggestion in several places over the past years:
If you connect your Mac Mini to a "grounded" computer monitor (through HDMI), you will most likely fix the problem.
My conclusion is pretty simple, HDMI carries ground and is able to ground your Mac mini. So I would really recommend buying a monitor with a 3 pin connection.
Click to expand...
It obviously depends on the monitor you use and is no guarantee to solve your issue but it's something to keep in mind.

How to Ground a Mac Mini (for music produ… - Apple Community

discussions.apple.com discussions.apple.com
 
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Hello, mine makes exactly the same noise. I have a Mac mini M4 Pro. The noise is constant, even when the computer is turned off. However, you just need to be close to it to hear it. I guess that’s normal.
 
100% GUARANTEED way to "end the buzzing" when off:

Get a power strip or surge suppressor.
Plug the Mini's power cord into it (along with other accessories, such as the display, etc.).

When you're done with the Mini for a while, and want it off (and quiet):
- shut down the Mini
- reach down and flip off the power strip.

No noise. Guaranteed.

This post has no "/s" at the end.
I've actually been doing this with my Macs since I first got a Mac SE, back around the spring of 1987. I'll keep doing it until... well... until "the end".
 
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I finally figured out where the problem was coming from... it's when you plug the screen in. Doing a quick search, it seems I'm not the only one.
 
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sauria said:
If you plug the two prong outlet into a grounded surge suppressor does this mean that your mini is grounded?
Click to expand...
I interpreted @Fishrrman to mean that any powered accessories connected to the Mac should also be getting their power from the same power strip. Similar to how audio equipment can have a buzz sound when components are plugged into different circuits (a reason why optical toslink can be handy).
 
CharlesShaw said:
I interpreted @Fishrrman to mean that any powered accessories connected to the Mac should also be getting their power from the same power strip. Similar to how audio equipment can have a buzz sound when components are plugged into different circuits (a reason why optical toslink can be handy).
Click to expand...
Yes, and I'm curious if having this plugged in indeed grounds it to the wall (mains). No U.S. Mac mini that I have had since 2010 has a grounded plug included.
 
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I can’t imagine how frustrating the noise must be. If the display is connected via HDMI, a galvanic isolator might help resolve the issue.
 
Ascn said:
I do not have grounding, I am from the EU, Austria.
Click to expand...
EU outlets are available with a third grounding prong. The third appears as small metal tabs at the top and bottom of the outlet.

Another thing you can try immediately is to reverse your power cord in the outlet. That is, remove it, turn 180 degrees, and reinsert, if possible.

Question: When it is buzzing, how does it feel when you run your finger on the metal casing? A slight friction feeling, which goes away if you unplug the unit?
 
Alameda said:
Another thing you can try immediately is to reverse your power cord in the outlet. That is, remove it, turn 180 degrees, and reinsert, if possible.
Click to expand...
Or reverse it where it connects to the back of the mini, so yes, that's possible, even if someone's mini had a polarized plug. Edit: Oh wait, is there a different cord connector type on the back of mini in the OP's region?
 
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CharlesShaw said:
Or reverse it where it connects to the back of the mini, so yes, that's possible, even if someone's mini had a polarized plug. Edit: Oh wait, is there a different cord connector type on the back of mini in the OP's region?
Click to expand...
Pretty sure the Minis are universal except for the included power cord.
 
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Is this something one should worry about? Im on the fence buying a M4 Base model, but if this is a common problem I better wait. Not all shops offer the best return politics and issues like these sometimes can be hard to get return or replacement for :X
 
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