iPad Pro iPadOS 16.5 and weird GPU buzzing? (Update: It's my iPad case, not iPadOS 16.5)

[Nekomichi]

UPDATE: I suspect this issue is caused by my iPad case, which I received the same day as iPadOS 16.5 released. No need to panic about the software update. The original post is still kept below for the sake of context:

After updating to iPadOS 16.5, I noticed some weird behaviour with my devices and want to know if anyone else has also experienced these.

When doing anything that stresses the GPU, I can hear an electrical buzzing sound if I put my ear against the middle of the back of the iPad Pro around the logo (this is right under where the logic board is located, on the iPad Air/Mini the location will be along one of the long edges).

Using Genshin Impact as a control test, I noticed that the higher I set the graphical detail settings, the louder and higher-pitched this buzzing sound becomes.

Similarly, when running a GPU benchmark in Geekbench I can hear the same buzzing, but this does not happen when running the CPU benchmark.

Incidentally, I seem to be consistently getting about 5-10% higher Geekbench scores on all tested devices after the 16.5 update than before.

This was observed on three separate devices: iPad Pro 11" A12Z, iPad Pro 11" M1, iPad Pro 12.9" M2. Initially I thought it was a hardware defect with one of them but the fact that it happens on all three suggests something else.

Can someone else also test this please?

Edit: The sound is not coming from the speakers (it's audible even when volume is muted) and none of these devices were plugged into a charger so it couldn't be charger coil whine.

Edit 2: On iPad Pro, try listening right around the middle of the back, near the logo. On iPad Air or Mini or the 10th gen, try listening on the long edge where the Apple Pencil charger is located (or the front-facing camera on the 10th gen).

 

[Nekomichi]

Update: I think it's the power converter. One of the iPads buzzed way louder when it was in its case and originally I thought it was due to the back plate of the case carrying the vibrations better, but it turned out there was a magnet inside the case around the same position as the logic board inside the iPad, and the magnet was interfering with the power converter. I took apart the case and removed the magnet, which caused the buzzing to become a lot quieter (but it's still there). Incidentally, placing a magnet on the screen of the iPad near the middle causes the buzzing to become louder too. Not only could I hear it, the magnet even started to vibrate too. Please do not place magnets near the centre of your iPad.

I've included a video of the sound.

 

[darngooddesign]

I couldn't get my 13" M1 to buzz in my hand while playing Sky or Element.

 

[Slartibart]

I tried a iPad Pro 11" A12Z, iPad Pro 11" M1, both on iPadOS 16.5 - no buzzing (the iPads get hot… in silence). I use Moshi’s Versacovers which are full of magnets.

Btw. what power converter are you referring to?

 

[HDFan]

Using Genshin Impact as a control test

This was observed on three separate devices: iPad Pro 11" A12Z, iPad Pro 11" M1, iPad Pro 12.9" M2. Initially I thought it was a hardware defect with one of them but the fact that it happens on all three suggests something else.

Does it happen with other Apps?

 

[Nekomichi]

Does it happen with other Apps?

It happens with the GPU test in Geekbench 6, but not the CPU test. Occasionally it happens in the general iPadOS UI but that's uncommon. It seems like this only really happens when the GPU is being pushed hard but even then it's not that noticeable unless you really listen for it close to your ear.

Placing a strong magnet near the base of the Apple logo on the back during strenuous GPU use can cause the sound to become louder. One of the magnets in my case just happened to be in that place which was why it's so loud in the video. I cut open the case and removed the magnet and now the buzzing is a lot quieter.

 

[Nekomichi]

Update: I strongly suspect the issue is caused by my iPad case, which arrived the same day as iPadOS 16.5 releasing. While iPads do make some noise, it's not really noticeable unless a strong magnet is placed near certain positions and that's what drew my attention to the issue. My case is not MFi-certified and uses non-standard magnet positioning which could be why this happened.

I was incorrect in my earlier assumption that this is related to the iPadOS 16.5 update - sorry for the panic!

I've found teardown photos and X-ray scans of the 11" iPad Pro and have identified the specific components involved, and will update this post later when I've annotated the diagrams.

 

[Nekomichi]

Okay, here are my findings and what I think happened.

On the iPad Pro's logic board, there are a number of voltage buck converters, two of which I have highlighted in this logic board photo from iFixit:

These two voltage converters are positioned quite closely to a power management IC (that black square below them) and are likely used for regulating power supplied to the SoC. Even though this photo is from the A12X model, the M1 iPad Pro logic board has the same layout. When assembled inside the iPad, this X-ray from iFixit photo shows their relative position to the back logo:

As you can see, these chips are positioned right by the base of the Apple logo, which also happens to be where I can hear the electrical buzzing the loudest. These converters work by using coils and oscillating electromagnetic fields. Under normal usage, they shouldn't be audible however the nature of moving EM fields and coils means that sometimes it can cause vibrations (this is why our phone chargers sometimes make buzzing noises). When I took apart my iPad case, I found this magnet arrangement:

Notice how the circled magnet is positioned right at the base of the Apple logo on the back of the iPad? I suspect it's this magnet that's the culprit. When a magnet is held close to a voltage converter, it can cause the internal vibrations to move at a higher amplitude, which is why it makes it slightly louder. However, the voltage converter is also having an effect on the magnet itself. Remember those EM fields we talked about earlier? They're oscillating around the magnet, resulting in a physical force which also vibrates the magnet and since this magnet is securely embedded in the middle of the hard case, the entire back surface of the iPad case is being driven in the same way a speaker diaphragm would, resulting in that buzzing becoming much more amplified.

I've since removed this one magnet from my iPad case and the loud buzzing sound has stopped.

 

[darngooddesign]

It happens with the GPU test in Geekbench 6, but not the CPU test.

Link to a specific test I can run to try confirm your theory.

 

[Nekomichi]

Link to a specific test I can run to try confirm your theory.

There's been a few new developments. I was completely wrong about iPadOS 16.5, turns out it was caused by very specifically placed magnets inside the cases I was using which happened to arrive on the same day iPadOS 16.5 released. Running these tests without the case wouldn't produce an audible sound unless your ear was placed right up to the specific spot in a very quiet room.

 

[darngooddesign]

There's been a few new developments. I was completely wrong about iPadOS 16.5, turns out it was caused by very specifically placed magnets inside the cases I was using which happened to arrive on the same day iPadOS 16.5 released. Running these tests without the case wouldn't produce an audible sound unless your ear was placed right up to the specific spot in a very quiet room.

Yeah, I tried putting my ear against the logo but couldn't hear anything on my naked Pro.

 

[JoPro]

I’m a bit late but had the same problem with my ESR Magnetic Rebound Keyboard Case 360, which seems to be the same as the one that Nekomichi uses. Thank you for your explanation and helping me find the cause of the buzzing noise Just returned the ESR and ordered a Logitech Combo Touch for my iPad Pro M2.

 

[CASCPAW]

Okay, here are my findings and what I think happened.

On the iPad Pro's logic board, there are a number of voltage buck converters, two of which I have highlighted in this logic board photo from iFixit:
View attachment 2206337
These two voltage converters are positioned quite closely to a power management IC (that black square below them) and are likely used for regulating power supplied to the SoC. Even though this photo is from the A12X model, the M1 iPad Pro logic board has the same layout. When assembled inside the iPad, this X-ray from iFixit photo shows their relative position to the back logo:
View attachment 2206339
As you can see, these chips are positioned right by the base of the Apple logo, which also happens to be where I can hear the electrical buzzing the loudest. These converters work by using coils and oscillating electromagnetic fields. Under normal usage, they shouldn't be audible however the nature of moving EM fields and coils means that sometimes it can cause vibrations (this is why our phone chargers sometimes make buzzing noises). When I took apart my iPad case, I found this magnet arrangement:
View attachment 2206344
Notice how the circled magnet is positioned right at the base of the Apple logo on the back of the iPad? I suspect it's this magnet that's the culprit. When a magnet is held close to a voltage converter, it can cause the internal vibrations to move at a higher amplitude, which is why it makes it slightly louder. However, the voltage converter is also having an effect on the magnet itself. Remember those EM fields we talked about earlier? They're oscillating around the magnet, resulting in a physical force which also vibrates the magnet and since this magnet is securely embedded in the middle of the hard case, the entire back surface of the iPad case is being driven in the same way a speaker diaphragm would, resulting in that buzzing becoming much more amplified.

I've since removed this one magnet from my iPad case and the loud buzzing sound has stopped.

Hey there,

I recently bought the iPad 13 M4 with the ESR Rebound magnetic case. One very quiet night while browsing on the iPad I loaded up Tidal and heard a buzz sound that lasted about 1 second every time I chose a new menu etc. Long story short and after hours of testing I have since came to the same conclusion that the magnets in the case are causing the problem. What I don't know is, will this cause damage to the iPad? I really love this case and haven't seen any others I like, so before returning it is it something I can live with and won't cause damage? Or should I return the case?

 

[Nekomichi]

Hey there,

I recently bought the iPad 13 M4 with the ESR Rebound magnetic case. One very quiet night while browsing on the iPad I loaded up Tidal and heard a buzz sound that lasted about 1 second every time I chose a new menu etc. Long story short and after hours of testing I have since came to the same conclusion that the magnets in the case are causing the problem. What I don't know is, will this cause damage to the iPad? I really love this case and haven't seen any others I like, so before returning it is it something I can live with and won't cause damage? Or should I return the case?

Should be safe, the sound is coming from your case and not the iPad.

 

[CASCPAW]

Should be safe, the sound is coming from your case and not the iPad.

Okay thanks for your help!