The mid 2017 21.5" model of the iMac is new and this issue isn't major, so it's not surprising that the few people who have sewn up their computers after an upgrade or fix either haven't encountered it yet, or found the true cause.

The problem is that after reassembly, the microphone input is faint and muffled. It functions, but barely, and is essentially unusable. The culprit turns out to be the adhesive strips used for reassembly. The frame of this iMac model seems identical to its 2012-2015 predecessors, so ostensibly the same strips made for these earlier models would work here too. However, the microphone has been moved from the top of the computer (near the webcam) to behind the frame at the bottom of the screen.

Note the location of the "4R" strip in the following picture:

https://d3nevzfk7ii3be.cloudfront.net/ig...

Now look at the location of where the microphone has been moved to:

https://d3nevzfk7ii3be.cloudfront.net/ig...

One can clearly see that the "4R" strip completely covers the microphone and the holes in front of it, deadening any sound picked up.

Knowing this, the solution is simple. Make sure the microphone works properly before using any adhesive. Then, apply the adhesive strips, but when laying down the "4R" strip, cut away the portion covering the microphone (and a little bit more from each side to be safe).

Hopefully, this post will save others from hours of exasperation! :)

Cheers!

⟐ Answered November 25, 2025 at 21:56 MST

⟐ Commented November 18, 2021 at 3:01 MST

This iMac was my father's and began having this issue last summer. It will simply power off completely at random - sometimes being able to be powered back on immediately, sometimes not turning on for an hour. This problem persisted for months and grew more frequent until it was happening several times a day.

Rather than try to deal with it over long distance, I had him buy a new iMac and took the old one with me to NYC. Took to Apple, who found nothing wrong.

I reformatted the drive, did a new install and step up with new software in a completely new environment - I did NOT restore from any user or backup. Within a week the Mac started shutting off again.

I brought it to Apple again. They kept the machine this time and ran diagnostic over days but could not get it to repeat shut down in their possession and insisted it was a software issue. We rebuilt the machine once more and tried again. This time it worked for a few months before starting to shut down occasionally again. At first just every few days, then nearly daily (oddly often around the same time in the afternoon), and then multiple times a day.

I brought back to Apple once more and eventually spoke on the phone with a master tech somewhere in the Midwest who also thought the "Geniuses" must be missing something and gave them more stressful test to try. Again, they can't get the machine to replicate the problem.

• This machine has been rebuilt several times.
• This machine has been in two completely different environments, with different sets of software from different sources.
• I have swapped power cords. I have tried different surge protectors and outlets.

I am at a loss and Apple will not tell me anything is wrong to replace.

Except for the shutting off, this still remains one of the fastest Macs I've used from probably 15 different 27" models from 2010 - late 2015.

Any suggestions? Thank you very much.

⟐ Commented December 02, 2025 at 16:00 MST

I used to use SM951 AHCI in Mac Pro 5.1, 6.1, all Retina and Air 2013-2015 but what about NVMe once? Have anyone tried?

⟐ Commented November 28, 2025 at 13:00 MST

So, I need a new card.

• Are all MXM 3.0 B cards compatible or does the card need Apple firmware?
• Would a 6970M card for a Dell Alienware laptop or another card with the same chip as one of the iMac 2011 models work?
• Where can I get a card that works? (<400$)

I've see a lot of questions and answers that dance around these questions but none that actually answers them specifically so ANY help will be greatly appreciated.

• ''Are all MXM 3.0 B cards compatible or does the card need Apple firmware?"
• "Would a 6970M card for a Dell Alienware laptop or another card with the same chip as one of the iMac 2011 models work?'

I found out Apple uses special firmware and for a card to work it needs an EFI flash with Apple firmware.

A card without Apple firmware will simply result in a black screen.

A friend of mine did suggest I could remove the BIOS/EFI-chip from the original board and reflow it onto a cheaper card - but that will probably be too complicated for a lot of people and I already had a new card on the way.

Cards that already have Apple firmware (pulled from iMacs) are interchangeable though - I upgraded from the 1GB 6970M to the 2GB version.

• "Where can I get a card that works? (<400$)"

You can get a working card on Ebay or Aliexpress - any MXM 3.0 card pulled from an iMac should be fine. I paid ~300$.

Lastly, as @mayer pointed out, if you have an iMac 27" Mid 2011 with issues, the GPU is most likely the cause and Apple will fix it if it's no older than four years, because it's a recognized issue.

Apple refused to fix this one because it was sold in 2011 but if you want to fight Apple, maybe that'll work too - I chose to fix it myself instead.

⟐ Commented July 31, 2024 at 10:24 MST

After that the iMac doesn't boot properly. It does the chime sound, then the apple logo with indicator and then just goes to a white screen. The keyboard doesn't work as caps-lock light wont come on.

I have tried the following:

• RAM reset (Cmd+Opt+P+R)
• SMC reset (unplugged power source for 2-3 hrs, held down power button for 10 sec)
• Removed ram cards and powered up, it did the SOS beep with 5 second intervals, so I'm guessing logic board is fine
• Holding down Option key during startup brings up the disk selector (I have 2 partitions one with Lion and one with Mountain Lion) neither boots up.
• Tried booting from an external Mountain Lion Install USB drive, it shows up in Disk Selector, am able to select it, but then it stops at white screen
• Ran a thorough Apple Hardware Test off the internet through ethernet cable, took 1:45 hours and it showed no errors
• Tried to run through Mountain Lion Recovery Disk, same white screen
• Entered sIngle user mode (Cmd+S) and ran fsck -fy on boot disk, it gave a few minor errors, so I repeated fsck -fy a few times until it no longer gave errors, still doesn't get past white screen. I'm able to browse the HDD in single user mode using the shell. Then did "exit" and also "reboot" commands, both ended in white screen.

I've looked around and found several guides dealing with this exact problem, but as you can see from the elaborate list above, none of those remedies have worked for me.

Any help is greatly appreciated, I'm on a tight deadline to finish this animation project and this is the only machine I have access to at the moment.

I don't have Apple care nor warranty and there's no Apple store/Genius Bar nearby.

⟐ Commented March 12, 2024 at 14:44 MST

I installed 64GB of RAM into my iMac 4 x 16GB

After the upgrade the system fails to boot. I can hear the hard drive, however the screen is off, with the old RAM the iMac works as expected.

I have verified that the RAM is compatible and should work with my iMac.

Any solution to get the iMac to work with the new RAM?

⟐ Commented April 19, 2024 at 12:48 MST

This is the SSD that I ordered: http://www.newegg.com/Product/Product.as...

I am currently booting off that SSD, which is connected via USB 2.0, and I believe that it's being bottlenecked by USB 2.0.

⟐ Commented July 18, 2021 at 10:30 MST

⟐ Answered April 09, 2025 at 1:30 MST

⟐ Answer edited December 14, 2021 at 12:22 MST

I would be happy to post a 'technique' article showing people how to access and test the power supply in this model if someone can help me determine their proper output values.

⟐ Answered October 03, 2025 at 13:40 MST

Thanks! -Zach

⟐ Commented June 21, 2024 at 21:01 MST

⟐ Commented May 24, 2020 at 20:56 MST

I was wondering if I can upgrade the graphics card to a more powerful one, maybe to the ATI Radeon HD 4850 graphics with 512MB.

And if so, are there step by step instructions on how to do it?

⟐ Commented October 09, 2024 at 4:02 MST

⟐ Answer deleted September 08, 2018 at 1:32 MST

So... The New Intel CPU 8700K is now available!

I just want know can I replace my i5 7600k to the new i7 8700k?

Is it possible to upgrade?

Thank You So Much

⟐ Answered May 30, 2023 at 9:28 MST

My hdd is broken so I have to install a new one. Is it possible to install an SSD, and if it is, how is it done and which brand is optimal?

Best regards from Sweden!

Thomas

⟐ Commented June 03, 2020 at 4:12 MST

I got horizontal lines over the display! During the warranty period they replaced the board ( it blacked out ) and now this is happening. They refused to replace the device saying out of warranty and asked to replace it :-|. They were not even sure that changing the display will fix the issue. I am hesitant to replace the screen as I am better off to buy a new one rather keep repairing the faulty product.

Is there any way to fix it?

Tried
- Reinstall the OS
- External Display = Works fine
- Reseating those 3 cables

Lines kind of flickers, may be some lose cables?

Please help

⟐ Answered March 29, 2026 at 1:03 MST

But the main point I need the OS & software run it faster instead of need a largest storage. Just wondering is easy to change it to SSD if the specs is Fusion Drive not. Or get the SSD specs is better, so if need to upgrade in future is still feasible.

⟐ Answer edited April 20, 2024 at 14:32 MST

⟐ Commented December 06, 2025 at 5:34 MST