High CPU Usage of Macbook pro 16 2020 while connected to External Monitor

Question

High CPU Usage of Macbook pro 16 2020 while connected to External Monitor

Hi,

I am facing a very strange issue with MacBook after connecting it to an external monitor for a while the CPU usage goes high up to 80%, while I am using basic chrome for browsing. The activity monitor says its kernel_task which is taking high CPU as below image. The laptop has crashed and restarted a couple of times.

The machine starts behaving slow and it is difficult to even operate a mouse. I have connected the external monitor through C-type to HDMI cable and also with apple connectors, the same problem persists.

As soon as I remove the external monitor the cpu usage comes down within minutes. My system is up to date with latest Mac OS Big Sur 11.2.3 as below image.

Its really frustrating to use this machine. Please help.

Posted on Apr 24, 2021 5:37 AM

Reply

Answer 1

Sparks0829

Community Specialist

Apr 25, 2021 7:21 AM in response to nikhilmehta15

Hi there nikhilmehta15,

Thanks for joining us in Apple Support Communities! We understand you're seeing high CPU usage and your MacBook is performing slowly when you have an external monitor connected. We're glad you're here, and we can help.

Let's start by resetting the NVRAM and SMC on your MacBook to see if that makes a difference:

Reset NVRAM or PRAM on your Mac

How to reset the SMC of your Mac

If that doesn't seem to help, try the suggestions in this link and let us know how it goes:

If your Mac runs slowly

Cheers.

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Answer 2

Apr 28, 2021 9:44 PM in response to Sparks0829

Hi,

I believe the issue persisted in MacOS Big sur 11.2.3. However, I updated to MacOS 11.3, last night and haven't faced the issue till now.

I will monitor for two more days and update the same. I hope it solves the issue.

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Answer 3

Sparks0829

Community Specialist

Apr 25, 2021 11:15 AM in response to nikhilmehta15

nikhilmehta15,

Thanks for giving those steps a try and following up with us. We'd like to learn more, and continue working together to sort this out.

Did you get a chance to review the suggestions in the last link we sent? If so, what were the results exactly? For example, what do you see for available storage space on your Mac?

Next, which apps are you using when you notice this behavior? Does this ever happen when you don't have an external monitor connected to your MacBook? If you close all open apps on your MacBook with the external monitor still connected, does that seem to make a difference in the CPU usage you're seeing? Learn more here:

Quit apps on Mac

Also, let's see if this happens when you boot your MacBook up in safe mode. Learn how here:

How to use safe mode on your Mac

Send over these details, and we'll take a closer look from there.

Take care.

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Answer 4

Apr 25, 2021 9:37 AM in response to Sparks0829

Hi ,

Thanks for replying, I resetted the PRAM or NVRAM and SMC. But it did not work. The CPU usage again went high.

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High CPU Usage of Macbook pro 16 2020 while connected to External Monitor

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