Kernel_task used up all cpu% when charging

Strange. Often, a PRAM reset will correct this. Did you do the PRAM correctly?

1. Power down the machine.

2. Locate the following keys on your keyboard in preparation for Step 4:

‘command’ – ‘option’ – ‘P’ – ‘R’

3. Press the ‘power on’ button.

4. Immediately – and before the grey screen appears – hold down ‘command-option-P-R’ all together.

5. Keep them held down until you’ve heard the start-up chime twice. After you release them you should hear it again, and your Mac should boot up normally.

I would try it again just for good measure. If that still doesn't work, have you got any antivirus software or any other utility running in the background?

If you can reproduce the problem at will, I'd be inclined to take the mac and the power adapter to an Apple store and have a hardware check done. That doesn't sound like a software fault to me.

Same problem here. I think a heat problem also. I am on a 2011 15". I have modded the cd bay into my primary ssd drive bay - so i am running 2 ssd's which might have a heat impact. I also notice that when removing power cord cpu cycles drop but for me it is not imediate the cycles drop 30-60 seconds later. The process is using over 80% of all cpu's. I had no such problem in lion - only mountain lion. Solutions welcome!!

btw. maybe something to do with a vlc / safari interaction. in activ monitor PID is 0 kernel_task root and always 96 threads. When plugging power cord back in the cpu cycles do not jump up straight away. I am in hotter climates than normal at the moment but temps are still 20-30 degrees so well below operating temp for macs. Thanks

Same here. Macbook Air late 2010. Since I installed Mountain Lion, Randomly Kernel_task ***** 100% both cores.

I didn´t test unplugg power cord yet

I have had the same problem repeating over from Lion to ML. Oddly enought, it manifests itself pretty regularly on my iMac, but not my MBP (both mid-2011). A restart is the only thing that fixes it.

I have snow leopard installed on 1 ssd and lion on the other. I cannot replicate the error in snow leopard so I have to concur that it cannot be a hardware issue (whew I am out of warranty!) but it still does not solve the problem - having a 2011 machine i want / should be able to take advantage of the latest operating system. I run snow leopard for professional audio projects because it is to this day more stable than Lion and the "latest" operating system for day to day. Also have a windows partition and a linux live cd in the sd card slot. I only have this problem on Mountain lion. My feeling is heat managment issue and as milk suggests possibly related to 2nd graphics card use. I did not have this problem running lion and started to have the problem immediately after upgrading. I have opened the machine and cleaned all dust from inside / the fans this has made no difference. Would really like a response from apple on this problem....

been reading posts about heating issues. There seems to be some relation to java and heat issues. I think if i remember correctly i was prompted to install java after updating to mountain lion meaning that java is not part of the default os installation. Anyone with better knowledge than me have any ideas on this??

Am now running temp guage - will see if i can learn anything from this and report back....

If the kernel task is taking all your CPU, the first place to look is kernel extensions. Remove any 3rd party extensions.

I have 100's of kernel extensions installed - most of which i use ... is there an easy way to test them without uninstalling. Also for my general knowledge can kernel extensions have other related files in any other location apart from the extensions folder. if not i can test simply by temporarily removing them from the extensions folder - or can doing this destabilise the system? obviously i assume there is a laborious command line way of testing extensions?

Just found out that my Air Display software causes the kernel panic. Identified the Kernel extension as:

92 1 0xffffff7f816aa000 0xa000 0xa000 com.avatron.AVExVideo (1.6.4) <74 5 4 3>

97 0 0xffffff7f816b4000 0x5000 0x5000 com.avatron.AVExFramebuffer (1.6.4) <92 74 5 4 3>

An update of Air Display software fixed it

Maclogically wrote:

I have 100's of kernel extensions installed - most of which i use ... is there an easy way to test them without uninstalling.

Hundreds? I wrote a little diagnostic program that will list any active, non-Apple kernel extensions, among other things. Download EtreCheck from http://www.etresoft.com/download/EtreCheck.zip.

Disclaimer: Although EtreCheck is free, there are other links on my site that could give me some form of compensation, financial or otherwise.

Also for my general knowledge can kernel extensions have other related files in any other location apart from the extensions folder. if not i can test simply by temporarily removing them from the extensions folder - or can doing this destabilise the system? obviously i assume there is a laborious command line way of testing extensions?

Kernel extensions almost always have non-kernel counterparts with which they communicate. You want to do as little as possible in the kernel because it is very risky and very difficult.

10.8.1 update did not solve this problem......

Any ideas?????

Also have a problem where if the battery is completely drained computer starts up but is very unresponsive then goes to a black screen - whilst on power supply - sleep and does not wake from the sleep unless restarted.