Kernel_task hogging my CPU, over 300%

Question

Hi there, I was wondering if anyone can help me solve an issue with my mac.
I noticed that my kernel_task was really draining my CPU, hogging around 300%, barely leaving around 2% of RAM for the user. After doing a bit of research I found that kernel_task basically manages a load of extensions for your hardware and system programs.
Here's some pieces that i've learnt about the issues, as well as the steps that i've taken so far to try to resolve it.
- When I boot in safe mode the computer performs well, suggesting this could be a 3rd party extension issue
- Created a user profile, where the issue still occurs suggesting this is a 3rd party system extension
- Re-installed OSx to see if that would help it - nope
- Deleted the majority of my 3rd party apps, one by one to see if these were the issue. Still not fixed it as yet.
- I've not added any new RAM recently - I'm aware this can be a common cause of kernel_task issues
When I restart here's what the console is saying...
29/01/12 6:24:07 PM
[0x0-0xa00a].com.apple.iTunes[114]
error initializing gpu library
29/01/12 6:24:07 PM
[0x0-0xa00a].com.apple.iTunes[114]
AppleGVA:: Error creating the accelerator 1
29/01/12 6:25:15 PM
com.apple.launchd.peruser.501[90]
([0x0-0x34034].com.freemacsoft.AppCleaner[243]) Exited: Killed
29/01/12 6:27:01 PM
com.freemacsoft.appcleanerd[271]
Appcleanerd started successfully.
29/01/12 6:27:15 PM
com.apple.launchd.peruser.501[90]
([0x0-0x8008].com.apple.universalaccess[101]) Exited: Killed
29/01/12 6:27:15 PM
com.apple.launchd.peruser.501[90]
(com.apple.AirPortBaseStationAgent[112]) Exited: Killed
29/01/12 6:27:33 PM
com.apple.launchd[1]
*** launchd[1] has started up. ***
29/01/12 6:27:44 PM
com.freemacsoft.appcleanerd[44]
Appcleanerd started successfully.
29/01/12 6:28:23 PM
com.apple.WindowServer[69]
Sun Jan 29 18:28:23 Christopher-Edens-MacBook-Pro.local WindowServer[69] <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
Any help that you can give me is greatly appreciated.
Thanks!
Chris

Answer 1

MacBook Pro early 2011 2.3 GHz Core i7, 10.6.8. It had been running fine since I got it, but a month ago it started having those fits of sluggishness that many have described on this thread. Within a few days it was almost impossible to work on it. Activity Monitor was telling me two things: 1. iTunes was taking over 100% of CPU power — this was resolved as I have explained here:
https://discussions.apple.com/message/17681010
(note that I hadn't been aware that it was a thread dedicated to "iTunes for Windows" when I posted it).
2., Activity Monitor kept on showing peaks of anything between 500 and over 700% of CPU use by the kernel_task process, especially when watching full-screen videos on the external Cinema Display, when Firefox had many open tabs, when Spotlight indexing of a 1Tb external HD was going on, or when the battery was getting loaded.
A complete cache cleanup with Onyx did help briefly, but immediately after applying the latest firmware update, I was back to point zero.
Thanks to someone else's post, I followed another line of thought: the kernel_task process was maybe revving up because the CPU was getting too hot. It then took a bit more detective work and trial and error to figure that there was a vicious circle of sorts: kernel_task was going wild because it wanted to cool the CPU down, somehow, but its own hyperactivity was contributing to keeping the CPU overloaded.
The next logical step was to open the case (MBP switched off of course, and with due respect to all other precautions — iFixIt screwdriver kit highly recommended), only to find out that there was plenty of dust inside there, especially on both fans. I "scanned" the whole of it with the vacuum-cleaner's crevice nozzle, cautiously keeping it at a distance of 3-4 cm above the board (thus avoiding touching any electronic part). But I did apply the nozzle against the fans (one at a time), in such a way that the very suction had them rotate at high speed, and until all the dust was removed from them.
That was three weeks ago, and ever since my MBP has again been running like when it was born and purring like a happy kitten. Now the kernel_task process seldom runs over a single-digit percentage.
There seems to be a machine-specific aspect to all of this, though. Barely a meter away in this same office, there is a MBP, 3.06 Gb Intel Core 2 Duo, that is one year older, but otherwise with the same specs and setups, except for the fact that it has two external screens connected to it, not just one (but it's hardly ever used for heavy video streaming). Moreover, the resident cat shows a propensity to use its keyboard as a sleeping pad. We opened it too, and it had slightly less dust then the newer machine, still enough to make it worth vacuum-cleaning. Yet, this older MBP has never showed a sign of heating up and/or of CPU slowdown. Go figure…