The links found via [Wayback/Archive] macos kernel_task high cpu dual screen – Google Search were daunting.
In the end, the issue ways way easier to fix than I thought: open up your Intel MacBook (you need pentalobe screwdrivers for that), then with some compressed air, clean the dust (especially from the fans).
This post saved my day [Wayback/Archive] kernel_task takes up 500% of my CPU when plugging in external monitor – MacBook Pro 15″ Retina Display Mid 2015 – iFixit
Things I haven’t tried yet:
- Cleaning out more free space from HDD
- Using plain HDMI cable into the HDMI cable port
- Taking MBP apart and cleaning any potential dust
…
I faced the very same issue that you guys are facing and based on input from another forum decided to get my 2016 MPB fans cleaned out.
This made an immediate impact where when I connected my external display to the MBP.pre-cleaning, it would overheat causing the fans to spin at 6000 rpm or thereabout and the kernel_task would eat up 500%-900% of the CPU rending the system unusable.
This simple cleanup of the fans has allowed me to connect the monitor with no kernel panic anymore and even though the fans run around 5000 rpm now the CPU and GPU are running around 10 degrees cooler now.
The same picture is in [Wayback/Archive] macos – MacBook Pro high CPU with external monitors – Ask Different.
An even dirtier MacBook was at [Wayback/Archive] External Display – High CPU Usage – MacBo… – Apple Community.
Links that were interesting but unhelpful:
- [Wayback/Archive] If you’re experiencing the dreaded kernel_task CPU problem and are using an external monitor, try standing the laptop up on it’s front side. This solved my issue with kernel_task hogging all of the CPU. : mac
- [Wayback/Archive] How to Fix Your Mac’s “kernel_task” High CPU Usage Bug
- [Wayback/Archive] High CPU usage kernel_task with 2 … | Apple Developer Forums
- [Wayback/Archive] macos – External monitor causes very high CPU usage – Ask Different
- [Wayback/Archive] Kosmokaryote, the life thereof: [Technology] kernel_task consumes almost 100% of CPU on Mac OS X
- [Wayback/Archive] display – rMBP kernel_task spikes when connecting more than one external monitor – Ask Different
–jeroen
The Wiert Corner - irregular stream of stuff 