MacBook Pro 2015 overheating and slowing down

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Level 1

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MacBook Pro 2015 overheating and slowing down

I've got a huge problem with my MacBook Pro 2015 (15 inches). When it's getting hotter outside (today it's about 35 deg Celsius in Germany), the Mac gets very hot and slows down until you can hardly use it. I've installed the Intel Power Gadget and can see that the processor is throttled down to 0.8 GHz, which is the reason for the terrible performance. Just recently, I had the machine checked by Apple, and they swapped the motherboard. But even after this, the problem returned once it got warmer again. The only difference is that the kernel task isn't taking up lots of CPU power, the processor is throttled nearly immediately. I don't run CPU intense apps. Any idea what might cause this weird behavior? In Yosemite, I remember there was a trick to reset some setting .plist file, but this doesn't work for El Capitan. I also tried to reset the SMC, but to no avail.

MacBook Pro (Retina, 15-inch, Mid 2015), OS X El Capitan (10.11.6)

Posted on Jul 20, 2016 10:12 AM

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Answer 1

Esquared

Level 6

12,415 points

Jul 20, 2016 10:59 AM in response to derwaldgeist

Try Apple Diagnostics: Using Apple Diagnostics - Apple Support

Even if that doesn't find anything, the things you are describing cannot be right. Since the logic board was recently replaced, I'd go back with it.

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Answer 2

Esquared

Level 6

12,415 points

Jul 20, 2016 10:28 AM in response to derwaldgeist

Cannot be right... How does it behave in safe mode? OS X El Capitan: Start up in safe mode

And how does it behave in a new user account (log out from your current one).

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Answer 3

derwaldgeist Author

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9 points

Jul 20, 2016 10:33 AM in response to Esquared

Before I had the motherboard swapped, SafeMode was nearly unbearable. You could see every pixel being printed. Haven't tried it since the swap, but can do so. BTW: The temp returns to about 60°C when the CPU is being throttled down, but the throttle isn't released. I have to cool down the whole Mac to be able to work again.

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Answer 4

derwaldgeist Author

Level 1

9 points

Jul 20, 2016 10:48 AM in response to Esquared

I've tried the SafeMode now and even went into a cooler room. It behaves nearly as it did before the motherboard exchange. That means: Graphics display is very slow, and I can see graphics errors. For instance, if I open up Google chrome and put my cursor into the Google search box, I see a big blinking gray rectangle above it that pulses with the cursor. And also if I start Launchpad, I can see how the page builds up. It is not as bad as it was before the swap (I could see every pixel line being built up then), but it is not really useable. If I try to start a CPU intense application (in my case, a Node.js server), CPU usage climbs to max for some time and the fans run at max speed, before it calms down. If I do the same in non-SafeMode (in the same cooler room), the Mac can be used as normal. Any ideas what causes this? As I said, I had the Motherboard swapped, so I have absolutely no idea what error cause might be left.

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Answer 5

derwaldgeist Author

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9 points

Jul 20, 2016 11:00 AM in response to Esquared

Ok, I'll try it. BTW: According to Intel Gadget the CPU is now at 96°C nearly constantly, even in the cooler room.

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Answer 6

derwaldgeist Author

Level 1

9 points

Jul 20, 2016 11:04 AM in response to Esquared

The diagnostics test did not find anything.

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Answer 7

Esquared

Level 6

12,415 points

Jul 20, 2016 11:07 AM in response to derwaldgeist

That's the kind of temperature you'd expect in closed-lid mode while doing some CPU-intensive work. Not while doing some web browsing (if that's all you are doing).

Anything suspicious visible in Activity Monitor?

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Answer 8

derwaldgeist Author

Level 1

9 points

Jul 20, 2016 11:25 AM in response to Esquared

Well, I was running Node.js, which causes some load initially. But not for a long time. No, there isn't any suspicious activity visible. The only thing that I saw before the motherboard swap was the kernel_task, which sometimes climbed up to more than 1000%. But this is not happening any more since the exchange. BTW: The temperature cooled down after about 15mins, it's now running at 60°C, and the fan is also slow now (it was howling like a wolf before).

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