rMPR (early 2015) overheating after (clean) macOS 10.15 update

[cftbl]

Hi all,

I recently (against my better judgement) updated my early 2015 13" rMBP from OS X 10.11 El Capitan to macOS 10.15.4 Catalina.

Since then, I have been struggling against complete system shutdowns. Irregularly, but often immediately after powering on, the whole system locks down and shuts off. Often, this would occur repeatedly until I left the computer to cool down. After lots of messing around (including fresh install of Catalina and running from portable Linux), I belatedly realised the problem was overheating.

Installing a temperature monitor such as iStat Menus or TG Pro showed both CPU cores and associated sensor temperatures climbing well above 90 ºC, and into the maximum operating temperature (105) extremely quickly under minimal CPU load (just background processes such as Spotlight indexing, etc). The laptop has been cleaned with compressed air and dust removed from fan and heat sink. No, there are no background processes apart from Apple putting large loads on the CPU.

The system just did not turn the fans on to prevent overheating! Under system control, the CPUs rapidly heat up to very high temperatures without the fan even turning on. This occurred even with a completely fresh install of 10.15. If I do not manually force the fan on, medium or high CPU load rapidly causes the temps to hit > 100 ºC and the laptop to shut off.

The attached photos show two sequential system shutdowns, as recorded with iStat, where CPU1 hit very high temperatures immediately after login on a clean install, and the associated system-controlled fan RPM not spinning up at those times. This system was completely fresh, with only iStat Menus installed.

The problem is now controlled with the use of fan boosting within TG Pro, and I am now avoiding crashes by managing the temperature and CPU load.

The questions I have are,

1. Is it known that Apple have altered the system fan/temperature management protocols between 10.11 and 10.15?

I never previously had issues with random shutdowns, nor have I been aware of issues with overheating (although it may have been occurring as I have not previously monitored temperatures). The fan did turn on under heavy CPU load, as would be expected, but now even with prolonged CPU load and the sensor temperatures hitting the maximum operating level, the system does not turn on the fan.

2. Would rolling back from 10.15, to 10.14 or earlier, improve the temperature management, in regard to the system natively turning the fan on at lower temperatures/load?

3. Are there actions I can take to help the laptop stay cool? I am now using it suspended above the desk to keep the vents free and cool air circulating. Might reseating the heat sink, or applying thermal paste, or similar be a worthwhile action?

Thanks for your help.

 

[throAU]

The questions I have are,

1. Is it known that Apple have altered the system fan/temperature management protocols between 10.11 and 10.15?

I never previously had issues with random shutdowns, nor have I been aware of issues with overheating (although it may have been occurring as I have not previously monitored temperatures). The fan did turn on under heavy CPU load, as would be expected, but now even with prolonged CPU load and the sensor temperatures hitting the maximum operating level, the system does not turn on the fan.

2. Would rolling back from 10.15, to 10.14 or earlier, improve the temperature management, in regard to the system natively turning the fan on at lower temperatures/load?

3. Are there actions I can take to help the laptop stay cool? I am now using it suspended above the desk to keep the vents free and cool air circulating. Might reseating the heat sink, or applying thermal paste, or similar be a worthwhile action?

I have a 2015 13" MacBook Pro running Catalina here, it's a fresh install now (handed it off to the GF after my Air purchase) but it was running an upgraded install for the past year or so before that.

In answer to your questions:

1. Not that I noticed / not that I am aware? But its been a while since I've run anything else since Catalina came out - I'm normally a day 1 upgrader... (and that machine got the new OS every time as they were released)
2. I didn't have any significant random hangs/shutdowns that I can recall with 10.15. YMMV but I didn't have much of an issue with it for my use. I think I can recall maybe 1-2 hangs/unexpected needing to power up (e.g., went to wake machine from sleep, and it was OFF) in the past 9-12 months?
3. I'd suggest using safari for everything if you can instead of chrome. It might be popping off the lid to see if the fan/heatsink is full of dust/lint/etc. and maybe a re-paste might help, but haven't had to do that with mine so far.

If your machine is freshly installed it may be doing background tasks related to iCloud sync/photo import, etc. for a while but it should definitely not crash due to thermals if the hardware is OK.

If you went straight from 10.11 to 10.15 you may have missed some updates to the firmware, etc. that could have been part of 10.12, 10.13, 10.14? Might be worth upgrading to 10.12 then 10.13, etc in sequence to make sure that anything firmware related that was included with the earlier OS is installed in case it wasn't included in 10.15.

Having tried to resurrect a dead 2012 machine with Mavericks last month and upgrading it to Catalina, I'd strongly suggest trying not to skip a version of macOS if possible. At least in older versions, there were firmware updates in some of the releases around Sierra/High Sierra/ElCapitan that were not included in later releases. So it might be worth going back and upgrading in sequence... at least I'd try that before getting too settled into your new install - while you've presumably still got reasonably recent backups from 10.11.

 

[chrfr]

there were firmware updates in some of the releases around Sierra/High Sierra/ElCapitan that were not included in later releases.

This is not correct- firmware updates in Macs are not cumulative. Installing the latest OS and the latest updates for that operating system will get the latest firmware for a given computer.

 

[cftbl]

If your machine is freshly installed it may be doing background tasks related to iCloud sync/photo import, etc. for a while but it should definitely not crash due to thermals if the hardware is OK.

This is not correct- firmware updates in Macs are not cumulative. Installing the latest OS and the latest updates for that operating system will get the latest firmware for a given computer.

Thanks both for your help. I guess that's a point, but the issues did really start with the macOS update. I'll stay on 10.15 with a third party fan manager and see how it goes.

 

[throAU]

This is not correct- firmware updates in Macs are not cumulative. Installing the latest OS and the latest updates for that operating system will get the latest firmware for a given computer.

Not always. Not going back some years. Also sometimes they don't successfully apply.

There's an EFI version checking tool somewhere on the net I used last month which confirmed the firmware on the machine I was dealing with was out of date.

It's maybe a stretch, and I think more likely it needs a re-paste or a sensor has died somewhere, but you don't need to open your machine to reinstall different versions of macOS to test via process of elimination.

 

[chrfr]

Not always. Not going back some years. Also sometimes they don't successfully apply.

Some models may not apply firmware updates if there's an aftermarket SSD installed (and there's a longstanding bug with a particular iMac model), but the updates definitely do not need to be applied in order.