High CPU usage kernel_task with 2 monitors

Hi Junqueira,

The following should fix the high kernel_task CPU usage:

1. Disconnect both external monitors.
2. Shut down the Mac.
3. Plug in the MagSafe power adapter to a power source and to your Mac.
4. On the built-in keyboard, press the (left side) Shift+Control+Option keys and the power button at the same time.
5. Release all the keys and the power button at the same time to reset the SMC.
6. Press the power button to turn on the computer.
7. After fully booting into OS X, shut down again.
8. Press and hold the Command+Option+P+R keys immediately after you hear the startup sound.
9. Hold these keys until the computer restarts and you hear the startup sound for a second time for the NVRAM reset.
10. Release the keys and log in as usual.
11. Reconnect your external displays and keep an eye on the CPU usage.

Let us know if this fixes it for you...

Max.

Confirmed this help.

I was facing this problem a lot.My CPU usage would reach above 1000 percent and most of it would be by Kernel_task. Whenever we connect second display or use heavy applications ,it requires more gpu/cpu power so our computer heats up more. If the temperature rises too high, Mac Os will run a dummy process "Kernel_task" to reserve cpu usage but keep it idle to reduce load of cpu and protect the computer from burning. As the temperature lowers it will release the resources. The problem in my case was accumulation of dust in the CPU and GPU fan.It had probably sucked it through the side vents. I cleaned it and it works like breeze. I even changed the thermal paste on my CPU and GPU as it had become hard over time and excessive heating. Hope this helps.

Hello @RobbySingh, I suspect it might be the case with me as well. How did you get your CPU and GPU fan cleaned? Did you have to unscrew and open up your Mac Book?

@joeltom21, yes you need to open up your case. But, if you are in US, you can make a Genius Bar appointment at apple store and ask them to open you laptop and clean the fans. They don't charge for this and very safe way to do it as they have appropriate pentalobe screwdriver etc. I had exact same issue with with my MBP, where connecting external monitors would make a 2019 model useless duet o kernel_task cpu usage. When I got the fans cleaned at Apple store, my MacBook was back in game. I am now able to connect two monitors with no issues whatsoever. My MBP runs without any noise where as earlier it used to due to the dust trapped in fans reducing their cooling efficiency.

I was having this problem recently also. Depending on what year your Macbook Pro is... if you have the power (charging) cable plugged into the left side. I would recommend first trying to move the power to the right side of your laptop. This is apparently a known issue with 2019 MBP's especially with the 16 inch model. Also, I found that because i had purchased a magnetic adapter online for my power cable, when i removed it, the high kenel task magically disappeared. Id recommend trying the same!