kernel_task at 103%!!
Overheating on MacBook Pro’s is a rare problem, usually down to nothing more than new users mistakenly thinking the aluminium casing is supposed to feel cool to the touch. However, you know something’s wrong when the glass touchpad feels warm and the fan’s not even stirring…
When Finder and other apps start crashing, what might have been a small concern now starts to look like a real problem. You can try re-booting, but if you find that the reboot takes ten minutes or so and/or the keyboard doesn’t function at the login window, chances are your kernel_task process is running wild. If you’ve still got access to the desktop, you can check this in Activity Monitor, or use Terminal by typing:
>top -u
Normally, kernel_task won’t take up much more than one or two percent of CPU activity, so if you’re running at over 100% or you can’t get past the login window, its time to do a PRAM/VRAM reset.
Here’s how:
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 hopefully your Mac will boot up as it should and with the kernel_task process back to normal.
Tooltip: download and run smcFanControl in your ‘Login items’ to keep an eye on your temps and fan speed in the Menubar. 
Have you still got this problem, or found another solution? Let us know in the Comments! 
Related posts:
Why is my mac running so hot?
Why is my mac running so slow?
Also see:
Resetting the System Management Controller (SMC)
featured picture wormhole by IVIXIVIXVXII
Posted on December 14, 2011, in OS X Lion, Snow Leopard and tagged boot, cpu, disabled, frozen, hog, hogs resources, hot, kernel, kernel_task, keyboard, keyboard not functioning, list, login window, macbook pro, overheating, PRAM, processes, reset, resource hog, running, SMC, task, terminal, top -u, VRAM, wild. Bookmark the permalink. 2 Comments.
I have tried this numerous times to no avail, kernel task still running wild. I have uninstalled all unnecessary programme, deactivated everything but iTunes helper on startup options. This problem started overnight after a year of running perfectly. It was about 6 months ago I installed lion with no problems to date. Uninstalled all office for Mac as syncservicemagent showed up alot on then consul. It works like a dream with kernel task at ~ 2% at all times on
safe mode. It seems to be Internet usage that shoots it up to ~ 600 all of a sudden. I have rebooted my wifi modem. All above to no avail. My computer is almost unusable slow. CPU heat 30-31 c, ok I would imagine. Any help would be deeply appreciated!!
Hi Elena
Have you actually tried re-installing Lion from the Recovery Disk? Doing so will leave your user accounts and files in place (but do backup as a precaution!) and just reinstall the system files. If you made a copy of the .dmg installer when you downloaded Lion for just this kind of thing, please do NOT use it. Reinstall from a fresh copy of Lion by using the Recovery Disk.