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Released in November 2020, the 13" MacBook Pro features Apple's Arm-based M1 SoC with both an 8-core CPU and 8-core GPU. (Model A2338 / EMC 3578 with two Thunderbolt 3 ports)

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CPU constantly at high temperatures even when idling

I bought my macbook around 3 years ago and I noticed from the day I started using it that the fans were kicking in pretty often even when I wasn't doing any heavy or intense task. I brought it to an Apple reseller that checked it and said it was fine, so I went over it...

It's been a good amount of months now, probably more than 6, that the temperatures are clearly not right for my usage.

I was constantly at more than 50-55 degrees celsius, even when I had nothing opened. One clear example of the thermal issues that I'm encountering was when I had 4 firefox tabs opened and nothing else, literally nothing not even in the background (checked activity monitor), and the temperatures were bouncing between 90-100 degrees and the whole OS was lagging, and no they weren't weird browser tabs, I opened them on my friend pc since my mac was lagging as hell and they were totally normal web pages, nothing fancy.

Seeing some other forum posts and youtube videos, I decided to replace my battery and thermal paste. I used my mac constantly to write code so I did use it for pretty heavy tasks very often, the battery had around 900 cycles and I though that with my intense usage the thermal paste needed to be replaced.

Here is the thermal paste before replacement

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I bought the kits and replaced both, but it changed literally nothing. The temperatures are still very high, >50° when idling with no apps opened at all, easily at 95-100° with a standard code IDE opened, and from 60 to 75 with some simple safari tabs and Spotify.

I also ran benchmarks before and after the replacement and it seems that it is worse now? Before I was getting 4160 points and now I'm getting 4114 (with multicore), so the thermal paste wasn't the issue?

The only thing that I could have done wrong is putting an excessive amount of thermal paste on, but I don't think that is the issue, I'll attach a picture anyway just to make sure I didn't mess that up

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At this point I have no idea what the 'cause might be, I'll leave here a report of the temperatures while having some everyday apps opened in the background: Whatsapp, Todoist, Safari, and Spotify

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I just wanna understand what the issue is 'cause it's so frustrating. My friend has the previous 2020 model and he runs dozens of apps together while still staying under 50° degrees and it just doesn't make sense.

Edit: I forgot to mention that I wiped the OS twice to make sure that it's not a software issue

Answer this question I have this problem too

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Have you checked Activity Monitor to see if there are any background processes that are overworking the CPU? You could try to rule out software by creating a new user account, then testing to see if the overheating continues to occur when using the new user account. If the overheating isn't due to software, then that means it's being caused by a hardware issue. If you've already replaced the thermal paste and the battery and it's still overheating, then there might be an issue with your logic board or another component, assuming the interior of the computer and the fans are free of dust and debris. At that point you'll need to do some more advanced troubleshooting which could require swapping out other components for testing. Good luck!

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Yes I forgot to mentioned that I wiped the whole OS twice, and checked activity monitor of course. Any suggestion on what I should be looking for in the hardware?

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@giuliopime It sounds like there could be a problem on the board level that is causing poor heat dissipation—but I'm not sure what that would be or how you would go about fixing that. It might be worth trying to replace the entire heat sink or the fans before replacing the board, but I'm not sure what else you could do to minimize overheating. I suppose you could install software tools to manually control the fans, but that's not ideal! Good luck!

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Thank you for the info, will see if it makes sense to make such an investment . Cheers!

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@giuliopime - Did you note the low thermal value at the heat pipes? This is a sign of a failed heat pipe, time to replace the heat sink.

BTW - You also need to reduce the thermal paste.

Give this a try… take a single sheet of tissue, cut it to the size of the chips. Now wet it and roll it into a tight ball. Even this is a bit much in volume on what you need of thermal paste, it gives you an idea.

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What's the heat pipes sensor name?

Also, I've read that putting a bit too much thermal paste doesn't make it perform worst, if not by only a couple of degrees, do I really have to open it up again and reapply it?

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@giuliopime - HeatPipe Outgoing Air is the name offered in your image you have two one for each heatsink fin area.

If you don’t replace it the CPU will fail from heat damage at some point, depending how hard you push it.

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Ah I see, when I spin up for example Android Studio, the CPU goes at 100 degrees but that heatpipe temp stays at 40. Is that the air temperature of that area, and how bad is it if it stays at 40?

So you are saying that too much thermal paste is the issue?

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@giuliopime - You’re getting warm! Pun intended.

Within the pipes is a liquid, think of it like how your refrigerator works. The pipe prevents the liquid from escaping like how your frig does with it’s coolant. What happed is the liquid escaped! So the effective cooling is only what the pipe wall conducts to the fins from the CPU. Which is why you need a new heatsink part.

As far as the thermal paste, think it like your shower has a leak in the tiles. You buy a tube of sealant, all you need is a small amount to seal the hole. But! You just empty the whole tube spilling it all over the tiles and floor making a mess! Did that help? Now you have a bump in the floor to step on or the wall collecting water and soap!

Here we have the risk of the paste interfering with other parts. Some pastes are conductive or have a dielectric effect which can effect the CPUs support logic mounted on the carrier plate. And some are corrosive as well!

Best to limit it to the needed areas you only want the black silicon chips be covered not the areas in-between.

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Uh ok thanks a lot for the explanation. I guess I can try to reapply the thermal paste. Then maybe waste a few more bucks on a new heatsink hoping that it fixes the issue 🙏🏼

Thanks a lot

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have you tryed checking when your fan come on as that will be important because if the fan doesnt come on til the cpu is hot and by then it is damaging the cpu so try checking in bios for that.

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The fan seems to work properly

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Giuliopime will be eternally grateful.
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