Q: karnal task consuming 100% CPU on MacBook Pro Retina (Mid-2014).

Hello Friends,

I need your support to resolve a slow response problem I have been facing on my MacBook.

I have been using MacBook Pro retina (Mid-214) model, and facing a strange problem with my MacBook, sometime my MacBook respond very slow and when I check the hardware utilisation info I see that Karnal task is consuming 100% CPU.

I tried to observe the cause of problem and found that, it happen only when I connect power supply with MacBook, when I connect power supply, it work normally for 10 to 20 min but after that laptop temperature get raise up but fans keep the temperature under 60 to 65°C at 4000 to 4500 RPM but MacBook start responding very slow and karnal task consume 100% CPU, but when I disconnect the power, it take 10 to 20 min and start working normally.

I have reported this problem to Apple service centre and as of now they have taken these action to resolve the problem. but problem is still there.

1 :- Tested the MacBook with their software/diagnostic test. -- ( Nothing Found ).
2 :- Installed the fresh MacOS ( El Capitan ) -- ( problem Not resolved ).

3 :- Changed the Power adopter. -- ( Problem not resolved ).

4 :- MotherBoard is also changed recently. -- ( Problem not resolved ).

One more thing I have noticed that, it happen until battery charged till 80% and then it work fine.

Looking for support to resolve this problem which is impacting my work and day to day jobs.