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I have a Mid 2014 Macbook Pro, which was just serviced at Apple (battery replacement). While they were replacing the battery they cocked up the main board with CPU, RAM etc and replaced that for free. Here I thought - nice service, I got my old CPU/RAM replaced, almost like new my Macbook! :D

Obvisouly in the shop no issues were present for the n-minutes I examined it. Home, under a week of usage, started shutting down in a most peculiar way:

  1. Screen goes black, but still remains backlit for 30 or so seconds.
  2. Then the laptop fully shuts down

No apparent reason was found. So I went throught SMC and the memory reset procedures - no luck. Apples startup diagnostics alaso did not show anything.

Looking at shutdown logs I get latest a kernel panic with code -128 (RAM issues?): kernel: (AppleSMC) Previous shutdown cause: -128

So I wonder wtf is actually happening. I manage to write this entry while in safe mode, could it be a software issue still? Not likely installing unreal engine and quixel mixer caused the cockup... But am at a loss if -128 can influence that in any way.

Any tips? (Not sure if Apple provides warranty on repairs in case it is an actual RAM issue)

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  • I too have a Macbook Pro Retina (mid-2014) and it does the same thing. Did you end up figuring out what is going on?
    – Raqib
    Commented Dec 8, 2020 at 22:32
  • Sorry to hear that, I ended up going back to Apple, where they confirmed it was their fault, or more that the reinstalled logic board was faulty again. So they fixed it again.
    – guesXy
    Commented Jan 19, 2021 at 13:06
  • Thanks for the info. How much did the whole thing cost?
    – Raqib
    Commented Jan 19, 2021 at 15:51
  • I originally only paid for the battery replacemen (varies from model to model). Rest of repairs was covered by Apple, as they messed up the original replacement, or it was the faulty logic board.
    – guesXy
    Commented Feb 5, 2021 at 12:43

1 Answer 1

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Here is a post suggesting disabling the Thunderbolt Ethernet Driver solves the issue.

Another post suggests the nocrashmbp utility which says 2013-2015 MacBook Pros are susceptible:

The CPU has several power states and voltages. Some CPUs have become unstable at the extremely low voltage on one of it's cores. The CPU will sometimes briefly dip into that power state, and if it happens to be on the core wherein it is unstable you will see the “silent” crash. Screen goes black, a few seconds later it dies completely. This condition was observed with external test equipment, as well as through internal cpu voltage monitoring.

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