2 Replies Latest reply: Feb 15, 2013 5:57 PM by Linc Davis
LHiBP Level 1 Level 1

Hello everyone.


I have a small problem with my Mac which is about its fan noise and CPU usage.

It was running FLAWLESSLY until like last couple of days after OS update where I started to notice really high CPU and Fan usage.


But first, system specification:


1.6 Ghz Intel Core i5 Processor

4GB 1333 MHz DDR3 Memory

Intel HD Graphics 3000 384 MB Graphics Card

Mac OS X Lion 10.7.5

128GB SSD Storage


For some reason my MacBook Air started to have these "high intensity work" moments when a process called "Kernel_task" started to eat up to 600% of the CPU !


Now I can imagine it's just a software issue since it started to occur after I updated my OS via Software Application and my Flash Player and the rest of my software is up-to-date too but has any of you had this problem before ?


I do not play on my MacBook Air, there are only two things I do - I use Safari and some Adobe software (Photoshop/Flash/Dreamweaver/Illustrator/InDesign/Fireworks) and that's all.

MacBook Air, Mac OS X (10.7.5), MacBook Air 11"
  • LHiBP Level 1 Level 1

    Oh and I forgot about one thing - my Mac is not even hot so there is no way it's overheating.

    I can get it out from my protective sleeve after a day and it can run fine and the other day this problem occurs in random intervals of time, sometimes shorter and sometimes longer.

    Right now - there's nothing, it runs perfectly fine.

  • Linc Davis Level 10 Level 10

    The kernel is using excessive processor cycles. Below is a partial list of causes for this condition.


    When it gets high temperature readings from the hardware, the kernel may try to compensate by interrupting the processor(s) to slow them down and reduce heat dissipation. This condition can be due to an accumulation of dust, to high ambient temperature, or to the malfunction of a cooling fan or temperature sensor. Note that if the problem is caused by a faulty sensor that reads too high, there may be no actual overheating.

    The Apple Hardware Test, though not very reliable, is sometimes able to detect a bad fan or temperature sensor.

    Using Apple Hardware Test



    Transferring large amounts of data to or from an encrypted disk image or FileVault volume may put an extra load on the kernel. If both the source and the destination are encrypted, the load may be doubled. If you transfer data from an encrypted disk image on an encrypted partition to another such image on another encrypted partition, the load may be quadrupled.

    This issue probably doesn't affect late-model Macs with an Intel i-series, recent Xeon, or later processor. Those processors support hardware-accelerated encryption. You can determine what kind of processor you have by selecting About This Mac from the Apple menu in the menu bar.

    Installed software

    User-installed software that includes a device driver or other kernel code may thrash the kernel. Some system-monitoring applications, such as "iStat," can also contribute to the problem. You can test for this possibility by completely disabling or removing the software according to the developer's instructions, or booting in safe mode (with the shift key held down at the startup chime.) Note, however, that disabling a system modification without removing it or booting in safe mode may not be as easy as you think it is.

    Corrupt NVRAM or SMC data

    In some cases the condition has reportedly been cleared up by resetting the NVRAM or the SMC. I can't confirm.