Linked Questions

708 votes
16 answers
596k views

How to find cause of high kernel_task cpu usage?

Occasionally my machine will have a kernel_task instance max out the CPU: This can last from minutes to sometimes hours. The machine is effectively unusable in this state. Restarting doesn't help; a ...
Adam's user avatar
  • 12.8k
41 votes
13 answers
48k views

Why is kernel_task using so much CPU?

I have a Macbook Pro Retina with the following hardware: Model Name: MacBook Pro Model Identifier: MacBookPro11,1 Processor Name: Intel Core i5 Processor Speed: 2.4 GHz Number of Processors: 1 ...
Addison Crump's user avatar
38 votes
11 answers
98k views

OS slows down when I connect external monitor

I'm currently using a Mid-2015 MacBook pro and running Catalina's latest build on it. Although for quite a long time anytime I connect the MacBook to an external display via HDMI it seriously slows ...
TOLULOPE ADETULA's user avatar
39 votes
2 answers
39k views

rMBP kernel_task spikes when connecting more than one external monitor

When connecting a second external monitor kernel_task spikes to 600%+. This makes the computer unusable. Before Yosemite, this worked fine with 3 monitors. Here are the specifics: When I connect ...
vaughan's user avatar
  • 1,691
16 votes
3 answers
8k views

kernel_task hundreds of % CPU yet cpu frequency is being lowered

I'm trying to solve the mystery of a crazy high cpu usage on kernel_task. MacBook Pro (Retina, Mid 2012), 2.7 GHz Intel Core i7, Yosemite 10.10.2 I saw some advice to download the Intel Power Gadget....
justingordon's user avatar
6 votes
6 answers
15k views

Any reason not to run my Macbook Pro upside-down in clamshell mode?

My MacBook Pro gets stupidly hot when I'm working on it normally (not clamshell). I am worried that the heat could damage the screen if I use it in clamshell mode. I thought that I could place it ...
Andrew's user avatar
  • 243
7 votes
6 answers
20k views

Very high kernel_task CPU usage after updating to Yosemite 10.10.4

I updated to 10.10.4 on July 1, and ever since I've had very high CPU usage - roughly 270%, i.e. two and a half of four processors - by kernel_task. It appears on login for about five minutes, then ...
David's user avatar
  • 1,437
0 votes
2 answers
5k views

Mac at 100% CPU Usage when plugged into monitor

I just got this Asus 1080p monitor and I've connected my Mid-2014 13-inch rMBP (2.8GHz Intel Core i5, 16 GB of memory, Intel Iris 1536 MB Graphics, running El Capitan 10.11.6) to it via HDMI. The ...
owlswipe's user avatar
  • 5,922
3 votes
1 answer
897 views

Mac OS Big Sur | kernal_task usage is 500% when connected to external monitor

I'm facing a system lag issue whenever I connect to my external monitor, even though there is no user process. I have already gone through some of the answers in the stack exchange and did two things ...
Sathish's user avatar
  • 131
2 votes
1 answer
200 views

External monitor CPU usage

If i close my Macbook Pro laptop whilst it's connected to an external monitor of lesser resolution, will I have more CPU processing power as it's pushing fewer pixels?
Charlie Williams's user avatar