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Model A1419 / Late 2012 / 2.9 & 3.2 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac13,2

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iMac won't boot from SATA or USB (Can't find startup disk)


My 2012 iMac Intel 27" EMC 2546 is not working correctly.

I purchased the SSD upgrade kit and I cannot get it to boot. Below are the symptoms:

  • iMac does not show any disk in Startup Manager (holding Option at startup)
  • In recovery mode, the SSD is visible, but is not recognized as a startup disk. Verifying the disk shows everything is ok.
  • If the iMac is turned on without pressing any keys, the flashing question mark folder appears
  • The SSD does not work internally (connected to the SATA cable) or externally (connected by USB in the enclosure).
  • The old HDD was wiped but also cannot be read from the SATA or USB connection

Here are the steps that I’ve taken to remedy so far, without any luck:

  • Checked to ensure that the SSD was properly formatted. I verified its functionality by externally booting on a 2012 MBP and a 2012 iMac 21”. Everything is working correctly (running Mojave). Additionally, the enclosure and temp sensor are working correctly.
  • PRAM reset multiple times. Additionally, removed some RAM and changed the slots, and then went through the PRAM reset again.
  • SMC reset
  • Internet recovery through startup manager

This iMac was donated to me from work and was wiped before being given to me. Could this be a culprit?

My only other thought was the SATA cable to the board, but I’m not sure why it wouldn’t boot via USB.

Any help is much appreciated. Thanks!

Update (10/12/2019)

An update to this:

I purchased a SATA cable and when through the SATA Cable replacement guide here on ifixit. Everything has gone smoothly, but I still have this issue persisting.

Just to recap:

  • I have a new 2.5” SSD purchased from ifixit that is formatted correctly and has Mojave installed on it. This SSD is 100% working correctly as I’ve been using it with another 2012 iMac (through USB). I have ruled out the SSD as the culprit
  • I have a new SATA cable installed into the iMAC, but the same symptoms persist
  • The iMac powers up, but will show the flashing question mark folder (this is with the SSD plugged in internally to the SATA cable)
  • In recovery mode it does not detect the disk
  • In disk select (pressing option on startup) it only shows ‘internet recovery’
  • The mac was wiped before it was given to me; could this be the culprit?

Thanks in advance.

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On an external drive, any format will work. But internally it must be APSF or GUID to be seen.

Is this a blade drive or a 2.5” drive? Can you give us a link to what you bought.

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Hi Mayer,

The format for the drive is shows as APFS in disk utility, and I originally formatted it as GUID MAC OS Extended Journaled.

The SSD is 2.5" drive from the ifixit imac SSD kit (Crucial MX500 SSD). I can confirm that the SSD and enclosure are all operating perfectly. As I mentioned, I tested it on a 2012 MBP (through USB), and it's currently plugged into a 21" 2012 iMac right now and operating correctly.

I believe this seems to be an issue with the 27" iMac and not the drive, but I'm not sure what.


Try Target Mode. Use a firewire 800 cable hooked to each. boot the MBP, then boot the iMac holding down the T key. If all is OK the new drive should show up on the desktop of the MBP. If so you can now install a system to it from your MBP if you have one downloaded.


Hi Mayer,

putting it in target mode did not work. There is no disk visible on iMac when I tired the SSD in USB or SATA.


Please see my update from 10/12/2019. Unfortunately the problem still persists


Will the machine boot from the new SSD when using it externally with a USB to SATA adapter?


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On a boot up hold cmd R

Go into utility next go to disk utility select erase them format. It should now come up in the system.

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Maverick zal eeuwig dankbaar zijn.

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