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kernel_task using 500% of CPU. how to deactivate thermal throttling?

greetings

my mid-2015 15" macbook pro had become pretty slow and was running quite hot, and the battery was long-overdue for replacement. so i ordered some thermal paste and a fresh battery from ifixit - and spent half a day cleaning out the dust and scraping the old battery off the case and redoing the thermals.

i was very careful and everything seemed to go fine, but when i booted it up, the fans kicked in immediately and kernel-task was consistently sucking up 500% of the CPU. apple diagnostics identified a problem with the SCM - maybe 006 or 007? i can't remember the exact one - and said it was likely water damage. i ran a code (pmset? maybe) in terminal and it produced a report on the thermal throttling situation. it should be 100/100 if nothing is happening, but mine was fixed at 21/100 : OMG ! meanwhile, the computer is cool to the touch, and i installed tg pro which shows that none of the regions it monitors is above 40 degrees.

since then, through a very long and boring and sloooooow-motion week, i disconnected the battery and the trackpad and reattached them again. no change. i reset the SCM and the PRAM. no change. i also read 8723 articles online discussing this problem, and it seems like the best solution for me is to sack all the firemen and close down the fire station so they can't sabotage my life any more (or to put it less metaphorically, to de-activate the system which monitors the temperature and creates pretend work in kernel_task so as to stop me from doing any real work which might heat things up again - because this system is clearly broken, and has become like an autoimmune disorder rather than a sensible protection).

my question, then, is how to do this now we have big sur? there are umpteen tutorials online but they all date back a few years, back to when the OS was less paranoid about people poking around in its thermal underwear. a step-by-step guide for people who don't normally open up the terminal and run commands in it. or maybe some other suggestions how to solve this problem which weren't covered in the 8723 articles i already read, and won't require a repair which costs more than a new mac mini with apple silicon.

if you actually submit a winning answer, and my beloved computer lets me start doing (long-overdue) things again, i'll send you a bottle of wine. many thanks in advance...

ben


Update (07/25/2021)

Hello again

And many thanks for your support. And sorry for being slow

I redid the diagnostic test. PFM006. I'm not aware of having had any spills myself, but the notes that accompany this diagnostic say “usually the result of liquid

I tried to find the smc chip as per your photo, but I refused to let myself believe that the not exposed section meant the underneath. So I took out the SSD and looked underneath it and I also removed the heat dissipating bar again and looked under there

I guess I'll watch some YouTube disassembly tutorials in the next few days and see if I'm brave and competent enough to get to where I'm meant to be

In the meantime, the attached photo will show you how brave I've already been

Many thanks again

Slow Ben

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Update (07/27/2021)

@danj - journey to the centre of the earth completed. the smc chip was covered in some ugly dirt which i blew and brushed off. but alas, i rebooted and the kernel-task was right back up at 500% and the mac is still throttling me at 21/100ths of what i am hoping for

i am starting to lose interest, tbh. i’ve lost about sixty hours on this problem so far. do you think it is time to consider answering the question i first asked - namely, how can i de-activate this throttling with an OS as protective as big sur ? yes, i understand there are risks, but the other risk is that i give up on this mac altogether and buy a new one - and that seems very sad.

looking forward to your wise words

many thanks ,

ben

p.s. seeing as i disconnected the battery, i will zap the SCM and the PRAM now just in case
p.p.s. a before and after photo for you, plus a log of the pmset thing from terminal are attached. do you want to see more of the chip from different angles ? i was amazed how small and complicated it is so i took plenty. let me know

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Lets get a better idea on what's happening, restart you system and press the D key to enter into the onboard diagnostics. Let us know what errors you get.

Reference: Mac startup key combinations

さんによる

Thanks for the swift reply. I already did this test and it came back with an smc problem which it suggested was most likely because of a spillage. And the diagnostic code was something like pmf006 or 007.

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@benowenbrowne

Ben, I think Dan wants the exact code - not "something like". Help us to help you.

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@benowenbrowne - Did you review this guide? MacBook Pro 15'' Retina Display Mid 2015のロジックボードの交換 No need to watch YouTubes ;-}

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@danj boo! anything more to tell me?

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@benowenbrowne - Can you run it again and make sure you get the error codes. Guessing doesn't help ;-{

If you had a spill that can explain things! The SMC chip is at the exposed on the hidden side of the logic board. You’ll need to remove it and inspect for corrosion damage and if you had already cleaned the board you might have pulled off one of the small components. Until you fix your system hardware you really can’t move forward.

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Update (07/27/2021)

@benowenbrowne - To answer your question

Do you think it is time to consider answering the question i first asked - namely, how can i de-activate this throttling" SMC is the manager to the CPU of your system. You need it for the system to work.

Sadly, there is no easy fix here ;-{ Just like driving on a deflated tire won't work long either or get you going at a big speed.

We need to figure out why the System Mgmt. Controller (SMC) is having an issue. So either a sensor input is missing, wrong are in a failed condition. The dirt you saw is a clue! the other components on the other side also need to be inspected.

Maybe you've found the limits of your skills and patients. Time to put things back together and find someone local with the deeper skills and tools to fix your logic board. The other option is just replacing it https://www.ifixit.com/Store/Mac/MacBook... make sure you replace it with the same type your system is (IG for an IG or DG for a DG). While you can swap between the two other parts will be needed.

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Ben さん、ありがとうございました!
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