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Model A1419 / Late 2013 / 3.2 & 3.4 GHz Core i5 or 3.5 GHz Core i7 Processor, ID iMac14,2

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iMac stalls on bootup

Helping a friend with his iMac (emc2639). It was using Mojave at the time, when it froze, so he did a hard restart. Got the Apple logo, but startup bar would only go half way.

I tried all the usual troubleshooting (Disk Warrior, Disk Utility, Drive Genius), all come back saying drive is fine, but I still get the same result (startup bar goes halfway and stalls). Also will not boot into Recovery.

He said I could wipe it, so I did (I had to do this with it as a Target drive, because it also won’t boot from my installers). Got it restored back to Sierra, as that its the last one I can do with it as a Target drive. Same problem, get the chime, Apple logo, and then the bar stalls at halfway point. As a Target drive though, it will run my iMac just fine!! When I hold Option key, I see hd with my install, Recovery partition, and my High Sierra install disk, but it won’t boot to any of them. Wah!!

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Let's run the onboard diagnostics. Reboot the system and hold the D key. Let us know if you got an error code and what it was.

Reference: Mac startup key combinations


It came back saying "No Issues Found" (ADP000).

Then it gave me the "For More Information" stuff, and told me to click on "Get Started" for it to boot into recovery. I clicked on that, and I get the Apple logo, and a progress bar, and nothing is happening on the bar....


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Soluzione Prescelta

Sadly, you are hitting a failed dedicated GPU. In the older models it was located on a daughter MXM board so it was replaceable! In the newer ‘Thin Series’ it’s soldered directly on the logic board. The reason we can get part way in the POST process as well as run diagnostics is related to the onboard CPU chip graphics engine which is used at the beginning and in both both Diagnostics and Safe modes.

Here’s the needed part iMac Intel 27" EMC 2639 GTX 775M GPU Logic Board and here’s the Fixit guide Sostituzione scheda madre iMac Intel EMC 2639 27"

Immagine iMac Intel 27" EMC 2639 GTX 775M GPU Logic Board


iMac Intel 27" EMC 2639 GTX 775M GPU Logic Board


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Thank you very much, Dan. I have never been so stumped by a mac before. Feeling like you have tried everything, and getting nowhere, is mighty frustrating. Thanks again!


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macguy5150 sarà eternamente grato.
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