27" iMac Hard Drive Fan Problem

Dear all,

I am afraid to have the same. It started however with something different. About two months ago it started that my iMac spontaneously just switched off while working. I go only got it back on again by some reset procedure. After this happening 3 times I brought it back to the store for service, this was within warranty.

After a repair of 4 weeks with a new logic board (HD was said to be ok) I got it back at my home. All fine, could get it nicely on my network. However settings couldn't be saved anymore (e.g. deleting a network or switching the DHCP server) and I couldn't connect to internet. Network fine, some dns resolution but no internet. The helpdesk could only conclude that it "needed to go back to the doctor again". This was within 4 hours. After another 3 weeks I have it back now with a new HD - which is 1 TB where the previous was 500 GB - after about 15 minutes of simple work (Safari, some mailing) it starts to make a noise whether it is ripping a DVD. Very frustating given the history, I love my Mac for it's design but this is really bad.

Hi, Ali,

i tried copying your "/Applications/Utilities/smcFanControl.app/Contents/Resources/smc -k F1Mx -w 2af8" code into terminal, but i get a reply saying that
"-bash: /Applications/Utilities/smcFanControl.app/Contents/Resources/smc: No such file or directory"

is copying the code above into terminal the right thing to do or am i doing it wrong? i have the latest version of smc (2.2.2)

I have a 27 inch quad core imac with a 2Tb Hitachi drive, had it from brand new since late october and noticed from the very start that after being switched on and booted up, the hard disk fan will start reasonably slow and quiet and gradually get faster and louder, 15 minutes will pass and the hard disc fan is running at 5000 rpm and is pretty loud, even though only running safari! Temperatures look ok at about 35 - 40 C all the time. the fan will run at 5000rpm until the imac is put to sleep or rebooted, when booted back up again, the process starts over again.

its always been pretty annoying but thought that was just something to do with having a quad core, but after reading up on it and seeing that it should be running fairly silently unless really stressing it, i know something isnt right.

anyone with any experience of this and getting it fixed in the UK? really cant have it sent to apple for them to poke at it for a few weeks, mainly because i cant afford the time without it with final year uni work deadlines looming, and the sheer heft of the thing getting it to a shop without a car. Really dont want to just get it swapped either as loading back all my applications and work will probably take longer than actually just getting the thing fixed!

cheers for any replies.

Many thanks to Ali! That 'solved' my problem with the fan.

@WEBBERdrum, you just had to erase 'Utitilies/' in the given path, because smcFanControl isn't installed into this folder. So try:
/Applications/smcFanControl.app/Contents/Resources/smc -k F1Mx -w 2af8

This worked for me and now my HD fan isn't noisy anymore 🙂

Tip: Instead of "2af8" which equals 2750rpm I am using "12c0" which equals 1200rpm. Now my iMac is quiet as it should be I guess 🙂
If the temperature gets up I set it back to "2af8".

Cheers

ah, of course! cheers for the help. its almost too quiet now, its quite unnerving! an now the fan noise has gone, i can hear the "stomach rumble that many people are talking about! gah! ohwell, at least this is a temporary fix until i can afford the time to get it checked out.

just out of curiosity...you know the code for resetting the fan back to the default maximum? just incase it gets a bit too toasty.

cheers again

thanks for making my life better with this code!!

When I did Apple Hardware Test i got error code : 4SNS/1/40000000:TH0D-9.000

Should I be alarmed? think this code does point to malfuncition of this particular sensor.

Message was edited by: hpx

UPDATE:

I have discovered that loud fan might be a result of an AirPort bug! Like said my HDD fan was at startup 2500 rpm and in a span of 10 min it would spin up to 4500 rpm.

First fix that magically helped was with Teminal and command line !

But when I switched off AirPort connection for internet and reconnected to network with modem the whole fiasco with fan resolved itself!!!

Im interested to know if anyone else could come to same conclusion !

Hey guys, I've tried almost all of the things mentioned earlier in this topic, however these only seem to be temporary solutions.
The fans start acting up once again.
According to smcFanControl - it's currently at 66 degrees Celsius - 5092rpm
The only thing that is running is Mozilla Firefox with 6 tabs in total (even with a single tab it creates the same vacuum-like noise)

I'm not the brightest when it comes to Apple computers but I've been trying to follow the "/Applications/smcFanControl.app/Contents/Resources/smc -k F1Mx -w 2af8"
destination via "Finder" but seem to be having difficulties.

I've created two screenshots as follows:
Resources
http://i1086.photobucket.com/albums/j459/PhyZix89/Screenshot2011-02-18at101618.p ng?t=1298024595

Resources -> Sources
http://i1086.photobucket.com/albums/j459/PhyZix89/Screenshot2011-02-18at101634.p ng?t=1298024574

...and I can't seem to find the "smc -k F1Mx -w 2af8" bit..
Can anyone point me in the right direction as to what I am supposed to be doing, because I'm pretty confused.

It would be very appreciated if someone could get back to me on this, as I feel so clueless.

Thank you for reading.

PhyZix, o gosh no no ! You do not have to open app. package! Simply have it siting there in Applications folder under your account. Just like iTunes or Safari. Let it be there and dont go opening its content with right click or however you did it.

Now just run the smcFanControl app. , its gonna pop up in top bar and give you readings.

Next step is open the Terminal app. that you can find in your Utilities folder
Now this is with like oldstlyle chalk board icon with arrow and underline , you cant miss that.
When Terminal app is opened you gonna get dialog pad with some numbers and your account name spelled out followed by bold gray vetical box.

Now just copy the path /Applications/smcFanControl.app/Contents/Resources/smc -k F1Mx -w 2af8 and press ENTER

The magic begins!!! the fans will slow down to 2700 rpm!

IF only you go and replace last 4 characters in that command line with 12c0 and press ENTER your fans will slow down to 1200 rpm!!!!!!! AWESOME

Note this! Everytime imac goes to sleep, or you log out, restart..... YOU NEED TO REPEAT THIS ACCTION!!!!

Finally what worked for me also is canceling use of Airport for internet connection and the fans never came up again and no command line action was required anymore

Its EASY and it WORKS!!!! Enjoy

Hmm.. That's strange..
I tried what you told me to do with the Terminal application, not 100% sure if what I'm doing is correct, but this is the outcome.

http://i1086.photobucket.com/albums/j459/PhyZix89/Screenshot2011-02-18at170227.p ng?t=1298048648

As you can see the RPM still exceeds 4000, even with the code entered.

Thanks in advance for any comments made to resolve this issue.

Ok I can see that you have entered the code correctly cause there is no error in terminal.

And I am really surprised this has not worked out right for you.

The hack with terminal would be just temporary solution anyways, I forgot did you say U have new machine? Is it mid 2010 27 inch???

It's not a new machine, no.
I bought it about.. 3 years ago.
I had this problem about a year ago, after i tried the removal of the power cord solution, it never became a problem.. Until now.

I think it's a 22"
The problems stated in this topic seemed almost identical to mine, so I figured I'd post my issue here.

Apologies if I shouldn't have done so.

U did right looking for your solution , I would really like to be helpful to you but maybe this is model dependent case . I dont know . I wish I would work for you! In my case i got it 3 days ago and brand new with that problem.

Thank you, I greatly appreciate your efforts. 🙂
I'll keep watching this topic in hope of someone finding an alternative solution.
If I myself find a way to resolve this issue, I'll be sure to post here.
Best of luck.

After countless days of effort on trying to fix the fan noise..
Downloading fan control programs, searching forums over and over, uninstalling and reinstalling Mac OS X.. and several other things..

My brother shook the computer.. & pulled out the power cable whilst the computer was still running. Just like that everything was fixed, even though I tried over 100 things! Apparently just shaking it fixed the issue?! I pulled out the power cord so many times, reset the thing code (forgot what it's called) and everything, to no avail!

Anyway, I hope this post helps anyone with a similar issue, even though I'm still confused about it. Good thing I didn't take it to the Apple store and saved myself a few pennies.

Happy browsing!

Glad you got it sorted! although i personally cannot and would not recommend anyone to pull out the power cord when the machine is running, this could cause damage, with regards to picking it up and shaking it, i hope thats not when power is still applied! i still wouldn't recommend doing, anyway glad your now sorted, i hope!