I had the symptoms you describe. Im my case it was OLD APC software that had my Fans at 5700rpn's and temps at the limit!!
Open activity monitor and show All Processes, Then see what is using all recources of the OS and Quit the process and see what happens, try to track down what incompatable software you have installed.
This worked for me... I went to APC's site found the legacy sofware Re D/Led it so I could get the Removal script that was included in the install DL pkg!!
Good luck or clean Install...
Thanks for your advice. Unfortunately, I carefully reviewed all the processes running, and the only significant resource drain comes from the 'kernel_task' process (160-180% as I mentionned earlier), nothing else really goes over 1% of cpu usage or a few 10s MB of memory.
I will probably try a fresh install tonight, but since this happened out of the blue (I closed the computer before going to bed, all was fine, opened it in the morning, and the fans went crazy right away), I'm afraid a fresh install won't really do much.
I just spent over an hour on the phone with Apple, and here is what we found:
- when starting up in safe mode (hold shift at startup), the kernel_task does not seem to run wild (~1%), however, the fan still runs at full speed.
- I have just made a fresh install of os x lion on an external drive, started up on it, and the problem remains the same, high fan speeds, kernel_task process at over 160% cpu usage.
Additionally to what I had already tried we did:
- repair disk
- repair disk permissions
- re-reseted PRAM and SMC
- removed all login items (except iTunesHelper)
As for spotlight, I can see the process running in the background, but it uses very little of the resources, so I do not think it is a problem here.
I am waiting for a call back from Apple now now that I finished the new install, I will post any further development here. Meanwhile, if you or anyone else has anymore suggestions, please let me know!
UPDATE: still no news from Apple, but I kept looking arround and eventually performed an Apple Hardware Test (hold D on startup, I didn't even know this existed) which found the following error: 4SNS/1/C0000008:TCOD--124. After some googling, it turns out this may be a heat sensor issue, although there is very limited references to that specific error code, and the only resolved case was achieved by turning the MBP off for a few hours (I've already tried that, desperate...). Sounds like I'm going to have to invest in Apple Care!
An Apple Hardware Test error that includes "4SNS" is a sensor error, and in your case I have no doubt it's a temperature sensor. That would account for the strange combination of cool operation and high fan speed, since whenever a temp sensor fails, the fan or fans run at full speed just in case the faulty sensor is failing to report a very high temperature that really exists in the machine. Usually there is no problem of excess heat in reality, but the fan speedup is a safety precaution.
What remains completely unexplained, at least to my way of thinking, is how your CPU can be getting the extremely heavy use reported by Activity Monitor without its temperature going far higher. I don't see how a faulty sensor can possibly account for that — in fact I can't think of anything that would.
The logic also escape my understanding, especially since the heavy cpu usage does not happen in safe mode!
Finally I heard back from Apple, and they are sending me a box to send the mbp for repairs, for the nice flat rate of $350, just one month after the warranty expired! At least they were very nice and helpful as usual, but this kind of timing is a bit annoying!
Thank you all for your answers and hepful suggestions. If I have a more detailed report from the hardware replacement I will post it here so that it may help people with similar problems.
So my computer is back and all fixed. They had to change the logic board and apparently they not only changed but also added some temprature sensors. If you want to get it fixed fast, run the Apple Hardware Test (hold D on start up, and if that does not work, use one of the 2 CDs that came with your laptop, the one that says AHT or Apple Hardware Test on it): this will give you an error message starting with 4SNS (if your problem is the same as mine), and if you just tell that to Apple on the phone, they'll have you send or bring your laptop to be fixed (flat rate ~$350 if you send it).
Good luck with that!
Backup your files before doing anything.
I had exactly same issue, on my part i've tried:
- Apple Hardware Test (No Faults Found)
- Format Disk and Fresh install of Snow Leopard.
- Resetting Pram.
- Resetting SMC
- Installing all updates
- Repair Disk
- Repair Disk Permissions
- Verify Disk
i was thinking to get new logic board. But finally i opened inside the MBP and replaced the thermal paste. It was dry and the screws that holds CPU and Nvidia Card was kind of loose. Then again it was on 2 years old MBP. It has been a week, MBP runs like new no issues so far.( knock on the wood. )
Hope this helps
I've had this same problem, CPU going insane, up to 500% usage, with the normal amount of threads, and the fan running full speed even though the temp was 91F or lower.
Eventually, I opened up the console and looked into what was calling the kernal task. It turned out Adobe Air was throwing a call on behalf of Adobe Story hundreds of times a minute. I uninstalled Story and the problem went away immediately.
So if you're like me and your hardware test checks out fine, have a look at the console and see if there's anything out of the ordinary.
I have the same issue (2.66 2010 MBP Hi-Res Anti Glare.)
I took it to Apple Store Covent Garden, JUST within warranty.
18 days later my machine has a new Main Logic borad, heat sensors, top case, palm rest. etc.
I turned it on.
The fans kicked in. All processors at 50%, big ole kernal task.
I took it back, geniuses rest SMC and tested it under load and it was fine.
weirdly it failed diagnostics at first but then seemed fine
I came home. Fans kicked in...
I took it back. Diagnostics failed heat sensors again
Replaced logic board and heats sensors again, but more carefully this time just in case, tested again.
I took it home. FANS FANS FANS.
Last time I was in the store I was told my machine was fine and had been thoroughly tested.
In mac store, no fans.
I erased hard drive and clean installed Lion
I replaced hard drive with OCZ SSD, clean LION.
Onyx complete clean/maintenace
switched back to Snow Leopard SSD
PRAM SMC ONYX etc.
replaced RAM, memtest-ed. fine, FANS
gonna try again but up to nearly 2 months of all my spare time trying to shut this thing up so I can sell it.
I have the exact same symptoms as you. Runaway fan, and high kernel CPU consumption unless I login to safe mode. However, fan keeps going.
I tried everything you tried and it didn't help either. I just did a hardware test (pressing D on startup) and unfortunately, that came back with no issues either.
I have a clean install of OS X now after I deleted my old install. Looks like I will have to take it to the Apple store.
I am convinced that it is a hardware issue and I am perplexed by how that can result in the software kernel utilization. Also, I don't understand why the kernel is ok when I login to safe mode but the fan keeps going.
Seems like some service that is responsible in tying the kernel to respond to the hardware issue is turned off when I login to safe mode. That's the best explanation I can come up with.
Hope the geniuses at the Apple store can find what's wrong.
In the end it turned out to be a faulty display cable.
I am not sure how this was tested for, maybe they could power up without the screen?
So if there is any sort of loose connection, and something seems to be missing, the fans go mad just in case.
Doesn't explain the CPU thng though.
Maybe it was a starting back from sleep thing.
2 months of silence now though so all seems good.
Apparently this is quite a common fault.
It's just none of the other geniuses knew that.
Obviously I don't mind having a new screen, top, logic board, senor, palm rest, side panel etc. but it's weird how long this took to diagnose.
Anyway.mention possible faulty or badly connected cables and see if it helps