4 Replies Latest reply: Jan 30, 2013 5:52 AM by Linc Davis
Christendean Level 1 Level 1 (0 points)

Hi, can someone please help me.  I am at the end of my rope.


My MacBook Pro 13"  2.4 GHz i7 , 4GB DDR3 RAM,Intel HD Graphics 3000 (early 2011 model),  OS X  10.8.2 (mountain lion)

has been driving me crazy for the last 2 weeks.


Its been excessively lagging & the fan is up at full speed. (constantly)

Its so loud its worrying.


Previously it ran so hot it would burn my lap, now its ice cold.


But the main issue is:


Activity monitor indicates constatnly CPU usage by system at  84% with NOTHING running!


Its seems like a runaway app, but i cant find anything.

Only the Kernel_task shows  324% CPU


My user usage is sitting around 2 - 7% ( 5 - 7% if i patiently try to run anything)


I've tried the PRAM & SMC resets, with no results.


I've spent 2 full days at my nearest iStore, only to be told they have no clue, its very strange & they cant help, they have to send it to some repair centre which wil take up to 4 weeks before i can get my macbook pro back.


I need it for work & studies. ( part time student, looking for part time work)


It did suddenly come right again last night and worked normally, but after i closed the lid and left it all night, it was back to the problem when i opened it this morning.


I cant afford to send it away for 4 weeks.


And this will be the 3rd time they've sent it away for mystery problems.


I need help to sort it out myself.



All help greatly appreciated, thanks


Desperately struggling

MacBook Pro, OS X Mountain Lion (10.8.2), Intel i7, with HD 3000
  • 1. Re: Can someone please help me,  my macbook pro is indicating excessive cpu usage
    Shootist007 Level 6 Level 6 (16,640 points)

    Don't close the lid and let it go to sleep. Shut it down when you are done using it.

  • 2. Re: Can someone please help me,  my macbook pro is indicating excessive cpu usage
    Christendean Level 1 Level 1 (0 points)

    Thanks will definitely do that in future.


    But how do i now free up the CPU?


    As rebooting, shutting down & starting up again, and smc & pram clears dont do anything...

  • 3. Re: Can someone please help me,  my macbook pro is indicating excessive cpu usage
    clintonfrombirmingham Level 7 Level 7 (28,655 points)

    Is kernel_task constantly using 300% or more of your CPU under All Processes?



  • 4. Re: Can someone please help me,  my macbook pro is indicating excessive cpu usage
    Linc Davis Level 10 Level 10 (117,920 points)

    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. You might, or might not, see messages like the following in the Console window:

    SMC::smcHandleInterruptEvent WARNING status=0x0 (0x40 not set) notif=0x0

    The timestamps of those messages (if any) indicate the times, since the log was last cleared, when a processor was being throttled due to high temperature.

    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.