Kernel Task Slowing my Mac

It is unusual for the kernel_task to use the CPU that heavily. Consider trying the following:

Firstly, repair your hard drive and permissions:

Repair the Hard Drive and Permissions - Lion/Mountain Lion

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Repair

When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported then click on the Repair Permissions button. When the process is completed, then quit DU and return to the main menu. Select Restart from the Apple menu.

Next do the following:

Boot into Safe Mode and see if you observe the same phenomenon. The restart normally.

Create a new user account and log into that account. Again check to see if the problem has stopped.

Let us know the results of these two tests.

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

Throttling

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

Encryption

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.

Consider quitting all your third-party running applications such as Chrome/Firefox.

I think you need to take your computer in for service.

Shut it down immediately and make a "Genius" appointment at an Apple Store. Most likely, the logic board will need to be replaced.

Do you have an idea how much the logic board costs?

That varies according to the model and the region. Typically several hundred dollars (U.S.).

Hi Linc,

I have seen that you give advice for people aboput issues like whats happening to me, and I wondered if you could give me some:

I am in kind of the same situation and it is driving me crazy! Lately, the kernel task of my MB pro early 2011 goes over 300% and so it gets almost useless as it runs extremely slow. I took it several times to Madrid apple store,and hardware tests, again more hardaware test, format,cleaning its inside, and total reinstallation of the OSX were performed several times without success: they find nothing wrong but later at home it happens again and again. No more apps installed, new OSX... it can only be hardware, right?

It led to awkward questions and situations as it didnt ever happen when in the apple store, but only at home. Anyway, genius bar people incredibly nice.

I kept insisting, going back and finnally after reading these conversations here and explaining about it at the genius bar, they accepted to change the logic board for me. But sadly, it is happening again, and now i just dont know what else to do. If i take it back to the apple store, i dont know what else to say or explain, so far no problem has been found but it keeps happening. It is so frustrating!!! It is such a shame to have to stop using my Mac normally it is all more than perfect, but once the fan starts sounding loud, i know its back and no more use for a while.

Can anyone help me or give me any advice?? I would really really appreciate it.

Thanks in advance (and sorry for my english) 😉