Q: 27" iMac Hard Drive Fan Problem

Dear All,

Same problem here (changed failed drive from Seagate to another Seagate) and noise. I thing I managed to make quick'n'dirty fix using these two apps and a script (see below). BTW, looks like a guy in UK sells that solution for £20 piece at http://www.hddfancontrol.com/.

Well, you need two apps (free):

• TemperatureMonitor by Marcel Bresink (thanks!), http://www.bresink.de/osx/TemperatureMonitor.html
• smcFanControl by Hendrik Holtmann (thanks!), http://www.macupdate.com/app/mac/23049/smcfancontrol

If you like to follow, you need:

1. Install both apps in Applications/Utilities
2. Put somewhere (e.g. in ~/bin) the script from http://science24.com/pielasze/mac/hdd_temp2fan
3. Put somewhere (e.g. in ~/bin) crontab file from http://science24.com/pielasze/mac/crontab
4. Open Terminac, "cd ~/bin" and issue command "crontab crontab", which sets the script to run every minute
5. Check whether the crontab is set OK ("crontab -l")

The script reads HDD temperature every minute and adjusts HDD fan accordingly. After few minutes fan speed should converge to a reasonable RPMs. Also, if needed, the cooling will be increased automatically.

Crontab (point 4) must be set just once, it will keep running the script permanently, also after reboot.

Caveats:

1. RPM scaling is arbitrary. I set linear dependence through from 1000RPM at 40C and 4000RPM at 60C. This may be wrong (works for me, however). Set it youtself in the script. You may make your disk quieter or cooler, at you option. No warranty of any kind
2. If you clear your crontab somehow (e.g. "crontab -r") the toy will stop to control fan without warning

Hope this helps. Below the script:

#!/bin/bash

#

# Get current HDD temperature. You need TemperatureMonitor by Marcel Bresink (thanks!)

# from http://www.bresink.de/osx/TemperatureMonitor.html

# Needs to be installed in Applications/Utilities

#

HDD_TEMP=`/Applications/Utilities/TemperatureMonitor.app/Contents/MacOS/tempmoni tor -c -l -a | grep "SMART Disk" | sed "s/.*: *//" | sed "s/ C$//"`

#

# Assume 40C is normal temperature. Anything over that is overheat

#

OVERHEAT=$(($HDD_TEMP - 40))

if [ "$OVERHEAT" -le 0 ]; then OVERHEAT=0; fi

#

# Scale the overheat to fan's RPM. Run 1000RPM at 40C, scale to 4000PRM at 70C

# Disclaimer: set yourself whatever you think is safe and/or reasonable. No claims, please.

#

RPM=$((1000 + $OVERHEAT * 100))

RPM4HEX=`printf "%04x" $(($RPM * 4))`

#echo "TEMP=$HDD_TEMP OVERHEAT=$OVERHEAT RPM=$RPM RPM4HEX=$RPM4HEX"

#

# Set target PRM using smcFanControl by Hendrik Holtmann (thanks!)

# e.g. from http://www.macupdate.com/app/mac/23049/smcfancontrol

# Needs to be installed in Applications/Utilities

#

/Applications/Utilities/smcFanControl.app/Contents/Resources/smc -k F1Mx -w $RPM4HEX

And the crontab file:

SHELL=/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin

#min    hour    mday    month  wday   command

*       *       *       *      *      ~/bin/hdd_temp2fan

Hi prc24,

Can you help me with the following? I'm having difficulty understanding what I should do for steps 2 and 3 which you mentioned. You said put it somewhere. Do you mean creating a script? If so, how should I go about doing it? Pardon the ignorance and thanks in advance.

2. Put somewhere (e.g. in ~/bin) the script fromhttp://science24.com/pielasze/mac/hdd_temp2fan

http://science24.com/pielasze/mac/hdd_temp2fan3. Put somewhere (e.g. in ~/bin) crontab file from

Found a new solution...

Try this out http://exirion.net/ssdfanctrl/

Hope this helps you too. It worked well for me and free...

I have a similar issue with a 1 1/2 year old imac27. I have brought it to the geniuses at the apple store four times.

The latest is that they say its a software issue.the tech went through all my programs and removed

Some older ones.

Thought it was corrected.i came home plugged it in and left it several hours later the fan kicked onto high.

I'm so frustrated withe apple.i personally own 4 iPads half a dozen iPhones and converted all my business computers  to apple.can anyone tell me how I can escalate this issue.i also have apple care.

Thanks

My suggestion is that you try what FluidSpin advised: http://exirion.net/ssdfanctr

Here's another vote for SSD Fan Control. I replaced the internal 1TB with a Samsung 830 series drive and had the noisy fan problem. OCZ Vertex 3 drives appear not to cause any problems. Wish I'd known.

SSD Fan Control allows you to manually set the speed of the hard drive fan (I set mine to 1100 RPM), but it doesn't show the temperature, at least not in my setup. So I also installed SMC Fan Control which shows temperatures in the Menu Bar. Mine have never gone above 35ºC.

I leave the Optical Drive set to Auto, but if I try that for the hard drive, it speeds up.

Before I came across this thread I also tried HDD Fan Control (works well, but costs $39); and also Fan Control and Temperature Monitor, but they don't allow controlling the speed of the fan to a fixed minimum.

So, if you've got a HDD noisy-fan problem, check out SSD Fan Control and SMC Fan Control. The two in combination will fix the problem. Then all you have to do is send a few dollars to the developers as a thank you.

Well done.

Just a few words to comment that I had done the same as you but for a different purpose.

As an active member of BOINC and participating in projects as SETI and Rossetta my CPU gets sometimes very hot due to its hard work all day long.

This is the reason I searched for ways to lower the CPU's temp. First I found SMC Fan Control and it worked ok, but had no automatic control: it shows the temp and revolutions of the CPU fan, which I try to keep below 60º Celsius at around 3500 revolutions. Then I found SSD Fan Control which does the same but only for HDD and ODD and I installed and also use it to control these two fans. I have realized that the higher the flow of air inside my iMac also helps to reduce the CPUs temperature.

The funny thing is that I also had to change my HDD for a 750GB Samsung, but fortunately had no problem with fan noise.

Best regards

Alberto

SSD Fan Control fixed my I5 3,0hz Imac malfunctioning fan. I tried them all and this one is effective and free!

http://exirion.net/ssdfanctrl/

Not sure about original post but I see people replacing HDD and having these problems.

If replacing HDD Use proper cable.

Finally there are options.

OWC sells (looks like the gravis)

http://eshop.macsales.com/item/OWC/DIYIM21HDD11/

Also this place...

http://thebookyard.wordpress.com/2013/01/24/the-aluminium-imac-ranges-and-their- hard-drives-2011-hd-problem-resolved/

That explains better... and link to purchase his cable.

Either of these allow to use any HDD in 2011 iMac with proper thermal sensor resulting in correct fan speed control. NO need to use software hacks etc.

How to deactivate terminal code? /Applications/smcFanControl.app/Contents/Resources/smc -k F1Mx -w 2af8 ??

I recently upgraded to a non-Apple supplied 2TB drive and while I was at it I put in an SSD for booting too, all into an early 2011 iMac 27".   The roumers about Apple using special firmware is nonsense, its simply a case that most HDD's have a built in temperature senstore but they call bring it out onto differnt connectors.  The sensor is a simple sliicone junction sensor, I used a 2N2907 TO-220 package transistor which costs around 10c as a replacement temperature sensor - no extra software hacks, and no fast fan speeds and temp sensing works perfectly.  The moificaiton I done to my iMac is completly reversible. I have been using the computer for a couple of weeks now and its flawless.  I put the whole execise on video on my blog, the link is below.

http://gerrysweeney.com/apple-27-imac-teardown-ssd-hack-and-2tb-upgrade/

Gerry

I have a mid-2011 27 inch Imac that I purchased in September, 2012.  It is still covered under Apple Care.  Based on reading this forum I think I may be having issues with the fan.  I took my Imac to the Genius Bar about four months ago and they replaced the hard drive.  I didn't have any issues for a few months, but now I am often hearing a spinning noise and the computer is pretty slow when I hear the noise.  My question is this something that Apple can and will resolve at the Genius Bar under Apple Care.  It seems based on the forums  it is a pretty common well documented issue.   My skills in trying to resolve technical issues with computers is pretty limited. I am not sure if I want to deal with paying for and installing applications to control the fan myself unless I absolutely have to.  Any input would be appreciated.

Thank you FluidSpin!

SSD Fan Control http://exirion.net/ssdfanctrl/

http://exirion.net/ssdfanctrl/

THANK YOUUUU!

¡GRACIASSSS!

I have had this problem for almost a year with my iMac 27'' 3.4Gh iCore 7. I was on the brink of turning to Windows to get over the hyperventilating fan that everynow and then slowed or simply stopped my Mac. I had tried expensive programs that did not work, combinations of tactics and reset of PRAM parameters, everything I could get my eyes on. Until I found Fluidspin and its incredible  SSD Fan Control http://exirion.net/ssdfanctrl/

http://exirion.net/ssdfanctrl/

I am back to having a superb computer and have my faith restored in Mac.

Thank you!

Miguel

I installed SSD fanc control.  Can anyone tell me how to use this.  What are the ideal temperature and rpm settings for hard disk and optical drive.  What temp and rmp should I be looking for under measured data in both?

Thanks in advance.