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2.26 or 2.4 GHz / White plastic unibody enclosure

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Why does the MacBook suddenly power off without warning?

The MacBook works in every way normally - boots normally, passes Apple Hardware Test with no errors, is normal to use… except it suddenly powers off, pretty much at random.

This sometimes happens during booting, sometimes happens within a few minutes of starting up, and sometimes happens after a period of using it. Intense processor use, and the heat of the MacBook, seem to make no difference (at least I cannot work out a pattern).

This has happened under two different versions of macOS, and using two different hard disks in the machine, and also having replace the SATA cable to the hard disk. The same happens when booting from a hard disk connected via a USB port.

Also going to Console and checking the logs does not reveal much that is helpful - here are the logs from the last two times it has happened:

When the computer suddenly powers off, a light sort of click/thud noise is heard. The MacBook will then reboot normally straight away.

This looks likely to be a hardware problem (a damaged logicboard?) but any further tips would be most welcome!

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Try to remove the battery, plug the charger and boot t he machine. If your problem is battery related the macbook should run ok. If the problem persist there’s probably an intermittent issue with a logic board component. The good news is that you can buy a used working motherbard for the A1342 for pretty cheap on ebay. If you have the 2,26 ghz version of the logic board buy the 2.4 ghz version fully compatible with your machine. Good luck :-)

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Note it will pretty much *always* boot, even with the battery connected. Sometimes it turns off while booting, but it has never not begun to boot. See my reply to @nick above - I will now test it with no battery, and with a battery I have spare here, and see what I get.

And yes, it's the 2.4GHz version, so I will replace the logicboard with that if it comes to it. 40 Euro + 20 Euro shipping to get one to me here in Berlin. So it could be a lot worse! :-)


OK, so it does exactly the same with no battery connected, and with a different battery connected. Just powers off every short while... So I reckon I better replace the logicboard.


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First thing to do is check the health of the battery - eventually when the batteries get on the old side, they tend to have little issues like this and either need to be recalibrated, or replaced. These are old enough it’s usually a bad battery but it can also sometimes come back with a recalibration run long enough to get some extra time out of the battery. For Macs, you don’t charge when the machine no longer boots - the difference between Mac and PC is PCs tend to shut off while Macs go into forced suspend mode.

If that doesn’t help, refresh the thermal paste. Get a tube of Artic MX-4 instead of AS5 for this laptop, since it’s not an easy job to correct a failed application and I have noticed in laptops AS5 degrades prematurely more then once, or an immediate application failure. AS5 will work, but I prefer MX-4 in laptops - even my easy to service ones.

MacBook Unibody Model A1342 Heat Sink Image


MacBook Unibody Model A1342 Heat Sink Replacement



15 - 30 minutes

PC Laptop Image


Recalibrating laptop batteries



12 hours - 1 day

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Thanks for the suggestions!

I will test with a different battery, and with no battery, and see what I get (I have a spare here - as old as the one in the machine, but it will do to test your theory). I'll then report back!

Re. the thermal paste - yes, I could do that, but in Macs Fan Control the temperatures are within the normal range - at low load the CPU is at about 50 degrees. Do I gain anything replacing the thermal paste in that situation - with regard to this specific problem? (Replacing the paste might make sense anyway, but I am not going to go through with that unless it will specifically help her). And note the power down is *not connected* to temperature or CPU load - it happens at low load and low temperature as well.


@jonworth After 3-4 years, it's shot on an older computer. If I pick up a used computer, I usually get it over with when I'm in there.

The problem is dead paste can cause overheat shutdowns, so if it isn't the battery the thermal paste is usually bad - providing it isn't a bad board.


@nick Can it cause overheat shutdowns even if the CPU temperature sensor is reading just 52 degrees C? Because that is what I am getting here... This machine is doing this at low load and low temperature.

Note that I have also now checked it with a different battery, and with no battery at all, and the result is the same - random shutdowns, sometimes after 20 mins of use, sometimes 2 mins, sometimes 20 seconds.


@jonworth It *could* run cool on the surface but have a serious heat issue.These are from 2009-10 so if it has never been done, it's been 10-11 years since it was pasted by the factory. Unless it has been serviced, the paste is dead on these.


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