Mac – kernel_task cpu usage 300% plus long press power button to start Mac Air

cpu usagekernelmacosx-yosemite

I'm having Mac Air 13inch 2014 having 4 gb memory and 120 gb Hard disk , from the few days i have been facing a problem that kernel_task is taking 300% of my cpu and my mac is running very slow and also it doesn't starts up until i press the power button for 30 seconds .

Things i have tried :

  • Fresh Installation of OS X Yosemite
  • Reset The SMC
  • Reset The PRAM

All in vain the kernel_task is still appearing and i also run the apple hardware test but it shows no Errors in Hardware .

What should i do?

Best Answer

This is Yosemite's way of cooling your machine.

Activity Monitor may show that a process named kernel_task is using a large percentage of your CPU, and during this time you may notice a lot of fan activity. This process helps manage temperature by making the CPU less available to processes that are using the CPU intensely. In other words, kernel_task responds to conditions that cause your CPU to become too hot. When the temperature decreases, kernel_task automatically reduces its activity.

https://support.apple.com/en-us/HT203184

The underlying issue may be another process, or even that the airflow is blocked, causing overheat.

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