Why is my 2015 MacBook overheating with no load?

Question

Retina MacBook 2015

Repair information and guides for the 2015 Retina MacBook Air. Model A1534

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tai att @taiatt

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crwdns2931729:0crwdne2931729:0: Kul 23, 2021

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Why is my 2015 MacBook overheating with no load?

I have a fresh install of Big Sur, and at room temperature, doing little more than having Safari open, I get a temperature warning, followed by the laptop going to sleep to cool down. According to the Intel power gadget, the temperature never rises above 55C or so. When it doesn’t sleep, the machine is running super slowly, unless I try to run it in the freezer, in which case it snaps to life. Any ideas?

UPDATE: Added photos:

When the first warning appears:

And a few minutes later when the second warning appears:

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Lets see if we can get a better picture on whats getting hot as well as why your system is not cooling properly. Install this app TG Pro you will likely want the full version here as you'll need the logging function to track things if you can't get a snapshot of the main window before the system shuts down. Post either here for us to see Adding images to an existing question

crwdns2934271:0Kul 23, 2021crwdnd2934271:0 Dan crwdne2934271:0

Added images of TGPro when the first warning appears as well as when the second one appears. The laptop goes to sleep shortly after the second warning.

crwdns2934271:0Kul 23, 2021crwdnd2934271:0 tai att crwdne2934271:0

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Lets see if we can get a better picture on whats getting hot as well as why your system is not cooling properly. Install this app TG Pro you will likely want the full version here as you'll need the logging function to track things if you can't get a snapshot of the main window before the system shuts down. Post either here for us to see Adding images to an existing question — Dan
Added images of TGPro when the first warning appears as well as when the second one appears. The laptop goes to sleep shortly after the second warning. — tai att

score 2 · Answer 1 · 2021-03-24T07:00:12-07:00

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Dan @danj

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Self employed contract worker

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crwdns2931729:0crwdne2931729:0: Kul 24, 2021

crwdns2933897:0crwdne2933897:0

mmm… I’ve seen some strange things! This one I think takes the top spot.

Your system is clearly not overheating when you snapped to captures. Time to visit an Apple Store as this is clearly a macOS Big Sur bug! Apple messed up the systems SMC firmware within the updater. Make sure you are clear the system was not having any problems until you upgraded to Big Sur.

I would even printout the two screen snaps you have here and you can also hand them this dialog as proof someone with deep knowledge of Mac’s clearly believes this is a firmware failure (one of three we have now discovered in Big Sur here on iFixit).

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crwdns2944067:05crwdne2944067:0:

It doesn't look to me like it's Big Sur's fault - it happened under Yosemite as well (the stock OS for this model). I performed a clean install of Big Sur in the hopes of solving the problem.

I bought this machine since I saw a good deal on it, and there's a return policy, so if there's not a software fix I'll probably just send it back. I'm fairly sure Apple's just going to quote me $400 for a logic board replacement or something.

crwdns2934271:0Kul 24, 2021crwdnd2934271:0 tai att crwdne2934271:0

@tai att - Return it then! If the problem was also under Yosemite then you have a logic board issue.

crwdns2934271:0Kul 24, 2021crwdnd2934271:0 Dan crwdne2934271:0

The other issue I noticed (I hadn't noticed it all this time since I was occupied with getting past the heat issue) is that there's no sound -- Mac OS doesn't even detect an audio device. I also noticed that the top right corner of the laptop (where nothing but the audio board is) is suspiciously hot. Could that be triggering the heat warnings? That would mean both problems are related.

I'm going to return the laptop mainly because I don't want to take a gamble in the hopes that I can fix the problem by replacing that part, but as an engineer I can't help but want to know what the problem is.

crwdns2934271:0Kul 24, 2021crwdnd2934271:0 tai att crwdne2934271:0

Update: I did a little experiment to test that theory -- I got an ice cube in a plastic bag, placed it on the top right corner near the headphone jack, and turned on the power. Ran it for a little while playing a Youtube video, no heat warnings and the CPU was not throttling. Took the ice cube away and had a warning in minutes, the CPU locked itself to 1.0GHz, and performance tanked. Put the ice cube back and within seconds the CPU stopped throttling and performance returned to normal.

crwdns2934271:0Kul 24, 2021crwdnd2934271:0 tai att crwdne2934271:0

Then the headphone board audio chip is failing! MacBook 12" Retina (Early 2015-2017) Audio Board the big chip on the back side is the CIRRUS DAC chip. There must be a thermal sensor on the board I'm surprised TG Pro didn't detect it.

crwdns2934271:0Kul 24, 2021crwdnd2934271:0 Dan crwdne2934271:0

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