HD spin down time

In macos9 it was possible to change the amount of time before the HD spins down, but in 10.4 there is only the option to spin down when possible. Even though I can change this setting with pmset in terminal, is there a reason why I should leave it alone? Usually when apple sets something, it is for a good reason.

I believe the factory set time is ~10 minutes but everything suggests this is an arbitrary figure.
I can see no harm in adjusting the time, as long as it's a reasonable adjustment - i.e. setting it too low would cause unnecessary wear and tear on the drive as it spins up and down constantly as you're using it. Set it too high and the drive will be spinning when it doesn't need to, consuming your battery. If you're plugged into the mains, and waiting for the drive to spinup after idling for a few minutes is annoying then certainly extending the time would be a good solution.
Repeated spin-up and spin-down of the drive is presumably worse for it's health than it spinning constantly or not at all, although I'm sure you'll find arguments for and against this.
If you don't want to change the setting in terminal, I think Cocktail lets you adjust this.
Rich

Similar Messages

Time Capsule will not spin down

I have read some similar posts regarding this issue, but none could I find that is similar to my issue. I have an older Time Capsule (model #1254) which I recently upgraded from 500 GB to a Seagate Barracuda ST2000DM001 2TB 7200 rpm 64 MB cache SATA 6.0 GB/s drive. Old drive was full. Since doing so the Time Capsule will not stop spinning, even when both of my computers are asleep or even shut down. The outside of the TC case is warm to the touch and I can feel and hear the drive spinning. The previous 500 GB Seagate drive did not have any of these issues.
Last night, while at home, I tried downgrading the firmware several times, but no luck. I have since read on the discussions to try renaming the TC and also, resetting the TC. I was hoping that someone else has had similar issues with a similar setup and has stumpled upon a solution. Obviously, I'm worried about the heat eventually killing my TC!
I decided on the 2 TB Seagate drive after reading other forums and discussions, but maybe I choose poorly?
Thanks all!

Hi, after some tests i went to a new situation, which allows me to spin down the disk, in certain circumstances. It took me a week, so I want to share this experience in case it would be of any help.
I executed the following operations using a MacBook Pro with a new installation of OS X 10.6 from an external disk. This is not necessary, but I wanted to exclude the possibility of some app or hidden process in my system, or even some unknown (to me) new feature of OS X 10.9 using the TC disk without my awareness. During all the test, no other device was connected to the TC network.
First, I copied the Time Machine spare disk volume from the TC to an external USB drive, via the USB port at the back of the TC.
Then I formatted the TC disk to all zeros and reset the TC configuration to factory default.
At this point, restarting the TC, the disk was spinning for hours like before, no change. But now I can exclude it was the OS X Spotlight indexing the files: with the disk formatted to zero, there was nothing to index. So, Spotlight is not guilty to for this buggy behavior of the TC.
Now what happened is that I mounted the TC with Finder, and, 5 minutes later, the disk stopped from spinning. I can't say if this would happen even if I wouldn't format the disk, as I don't remember the last time I mounted the TC as a remote disk. If someone has this problem, I believe this is the first thing to try, keep the TC mounted and see if the disk spins down.
Then I went back to my Mavericks installation, copied the Time Machine spare disk volume, perviously backed up to the external disk, back into the TC. And finally reconfigured Time Machine to keep on using the old backup volume.
Now Time Machine regularly backs up every hour, and 5 minutes later the disk spins down. But this only works when the TC is mounted as remote disk. Whenever I unmount it, and then backup, the disk keeps his old behavior and doesn't spin down.
I think it is out of discussion that the spin down command always comes from the TC and not from the Mac, because the default spin down time of OS X Mavericks is set to 10 minutes (and so is mine), while my TC now spins down after 5 minutes, according to his settings. So, the TC is able to spin down my non-original disk, but only when he likes. This means that if I disconnect my Mac from the TC network, and someone else connects his Mac to the same network, without mounting the TC drive, it will start spinning endlessly. This is definitively crazy.

Spin down / spin up External HD

Morning all,
I'm hoping someone can help me out on a request.
I currently run four external HD's at home, each with there own tasks and storage needs. I have set (using pmset in Terminal) my discs spin down times to 5 mins rather than 10, so these sleep quicker than normal when not used. I'd like to be able to spin down / spin up these disc's on instruction, rather than waiting the 5 mins.
I have put together Applescripts which I then build into Automator which I can run from Finder, and would like to have a simular script to spin down / up the drives on instruction.
I'm very new to writing scripts so this maybe something simple, but I just can't find a solution. Anyone got any ideas ?
Many thanks in advance.
Neil Holmes.

Sorry, I misunderstood you to already have the commands you needed for pmset, so I didn't look too closely at that command.
What I have determined is that you don't have the ability to force the disk to spin down immediately - but rather, as you have already discovered, to set the idle duration before it will spin down; the minimum being one minute. (I also noticed that to make a setting stick you need administrator permissions, so I have included that syntax here.)
I am not sure if this gets you any further forward, but the AppleScript syntax to spin down after one minute idle would be*:
do shell script "pmset -a disksleep 1" user name "<adminuser>" password "<adminpass>" with administrator privileges
and setting to never spin down would be*:
do shell script "pmset -a disksleep 0" user name "<adminuser>" password "<adminpass>" with administrator privileges
I am probably being stupid here, but wouldn't it be dangerous if you were able to spin down the disk on command?
*In each case, open Script Editor, cut-n-paste the text between the lines and amend for your username and password - retaining the double quotation marks, but not the braces - and click run.

MSI Z97 Gaming 7 + Annoying long CPU-Fan Spin-Down since 1.4

With BIOS 1.4 at time when i4790k arrived on market with their famous boxed coolers, MSI changed their BIOS to have a spin down-time for the CPU-fans of 5400 seconds or 9 minutes.
It is totally disgusting to have such a annoying new feature without an option to shut it off with decent cooling present.
I use the Scythe Mugen MAX and have plenty of powerful fans inside the case well arranged.... since 1.4 i feel like ripping of this vacuum cleaner and burn it with gasoline.
Is there any help in sight to make this frakk stop?

Well so what was the point of 3 posts if wanted only single modded BIOS? Also should've explained what you want from modded BIOS, not the problem.
The motherboard itself does support these frequencies, but not the CPU. And it won't run properly until you either understand it can't or find it yourself during hundreds of tests. You can keep trying, I wish you good luck running these frequencies but with all honest, there is very little chance.
You did run single kit, but did you try anything BELOW 2666mhz? You won't achieve anything through these frequencies. Also if you could try to run whole set of 4x8 with at least 1866 then you should be happy. It's out of CPU specs, not Mobo's. Can't deal with it to be fair that CPU can't support these. Also make note that if CPU can't support and doesn't work with it, then no matter how good is the mobo, it won't work properly.
Quote from: Incriminated on 12-August-14, 06:39:56
Please read more carefully and pay attention what you do... it might be considered as "Not helpful".
Sorry for trying to help. And paying attention after 19 hours without sleep is a bit hard, don't you think?

Time Capsule not spinning down

Ive searched this forum for answers to this - and all of them seem to be old. I am having a new issue where the TC doesn't spin down after completing a backup. Also, I just now powered down the connected computer and the TC continued to spin. This has never happened before, and just started a few days ago.
The internet part of the TC is working fine, both wifi and wired functions.
Thanks in advance for any help.

Motopreserve wrote:
Sorry, should have clarified. I use it for the time machine backups only - I was talking about makig a safety backup of these sparse bundles (I think that's what time machine backup is called) in case it s%#t the bed, and i needed to drag it over to a newer unit. Maybe that process doesn't work.
Copying the sparsebundles is possible but may not be worth the effort.. if you replace the hard disk, just keep the old disk as is. that is already your backup. It is really only to recover stuff that you think you might have lost.. but in general a backup will be only that.. a backup.
The unit is getting pretty hot during backups. I CAN keep my hand on it, but it's very warm.
I have not restored to defaults. Nor have I erased the drive clean yet. I was just going down the firmware route. Should I try resetting before erasing it? Or do both at the same time? I usually try to do one step at a time to see if I can narrow down the issue, but I'm fine with erasing it, and then resetting if there is no hope for one or the other to help.
The heat is killing it.. softly and by degrees.. both time and temp wait for no man.. or was that the tides.
I would say step 1. Restore defaults.. that is worthwhile.. do the full restore ie hold in the reset and power on.. keep holding in reset until you see rapid flashing led.. then allow it to restart. Redo the setup.
Step 2.. Firmware update will not fix it and could make it worse.. I would not do that at the moment. But there is no harm in trying .. you can always go back to earlier versions.
Step 3... wipe the hard drive. That is the final step and if that doesn't work.. well what is wrong can be power supply, hard disk or a combo of things.
Then take more drastic measures from there? I wouldn't mind replacing the hard drive myself, but is there any trickery to getting the firmware onto it on reboot?
Thanks for the thorough help!
Scott
Hard drive replacement is dead easy.. google for it.
But a few provisos..
1. Do not buy advanced format drive. Standard green 2TB is possible.. don't try for 3TB it won't work or is painful. Try and check what drives have been used successfully so you don't become the guinea pig.. I am all for lab rats but don't want to be one!!
2. Leave off the rubber mat. Just put some feet on the unit to keep it off the bench.. about 10mm should be plenty even 5mm is ok. (.25"-.5" in Imperial)
3. Just initialise the drive in the TC.. ie erase. there is no firmware on the hard drive.. but the TC will prepare it for use.
Consider if it isn't better.. with hard disks so much now, not to do anything.. erase the drive.. ebay it and just buy a new one.. I would be thinking hard along those lines.

Internal Hard Disk spin down - Mac locks up

Hi.
Recently my iMac has started to occasionally lock up. The other evening it was quiet and I heard the hard drive spin down. Following this any action results in the beach ball, and eventually everything locks up, because it cannot read from or write to the disk.
I have tried disabling hard drive sleep. Reseting the SMC and PRAM.
Not sure if it is related, but I also noticed that the system profiler reports that the last hardware test was run in 4008 (I'm sure it used to say 2008). So I ran a hardware test, no problems. The last hardware test date is now reported as 28th June 4010. Hmmmm.
Any thoughts on this, or help as to the next step will be very happily received.

It is normal to see the spinning beach ball cursor while the drive spins up, but obviously it should go away once the drive is spun up & the iMac should not eventually lock up.
Also, not every drive honors the spin-down command from the OS -- some spin down automatically according to their own internal timer regardless of the system preference -- but AFAIK no drive Apple ships in any Mac does this.
So just to cover all the possibilities, can you confirm that your iMac has the original internal drive it shipped with, & that there are no external drive(s) attached to it? If you do have any external drives, does the issue persist if they are unattached?
You might want to run Disk Utility's Verify/Repair Disk step on each drive you use to make sure a file system issue is not involved, & the Apple Hardware Test (which will require removing any non-essential peripherals like external drives & thus not test them) to see if a hardware issue is causing this.

External hard drive spinning down (and up) on it's own

I thought my 5 month old external 1tb dual drive was dying at first, but now am seeing a pattern. There is a forum over at macrumors about this. http://forums.macrumors.com/showthread.php?p=445690
I always make sure in my energy settings i have spin down external drives unchecked, because it's known that spin downs and ups can cause drives to fail sooner. Yet I now find my external drive spinning down whenever it's not in use while I'm sitting at my computer, and i hear it spin up at the most random times, even when i'm not using my computer. sometimes in the middle of the night. This did not happen in tiger.
It's connected by firewire 800. At first I thought it was time machine but others in the macrumors forum claim it isn't that. I almost think its network activity. I'm considering using an applescript to access the drive every 5 or ten minutes automatically yet not do anything just to see if this stops it from spinning it down. I do consider this an annoyance and would hope apple will figure out what it is very soon, before it causes any detriment to the life of my expensive drive.

did you ever find a fix for this?
my ext FW800 drives constantly spin down, then when i do something later i get the beachball until they spin back up

Hard drive spins down and have to do a hard reboot

I have an Intel iMac 3.06 (April 2008). Ever since I upgraded to Snow Leopard especially when I am using itunes (9.02) (downloading) the hard drive spins down for no reason at all.The energy settings are fine. The only option I have is to hold the power button down for 5 sec and reboot when it happens. I know this has been an issue with other intel iMacs but when the "fix" for other machines was available it said my machine did not need it. I beg to differ. This is getting very annoying as I am sure it is not doing the hard drive any good having to hard reboot all the time.
I have tried the power management reset which has not resolved the problem.

Hi David
Welcome to Apple Discussions
1. In the Energy Saver preference try setting Computer sleep: to "Never" and make sure the the box "Put the hard disk(s) to sleep when possible" is unchecked.
2. Try resetting the System Management Controller as described in the article below.
http://support.apple.com/kb/HT1543
Now then if you are still having a problem you might also:
1. Use the Restore Default button on the Energy Saver preference panel and then reselect your sleep settings.
or
2. Go to: Macintosh HD > Library > Preferences > SystemConfiguration and trash the "com.apple.PowerManagement.plist" which also restore's the Energy Saver preference to default, then go back to the Energy Saver preference and reselect your sleep settings.
Dennis

Apple software RAID 0 not spinning down while not in use

I have a G-Tech G-RAID w/ Thunderbolt, 8TB external enclosure. It has two 4TB fujitsu drives in it, set up as RAID 0 with Apple's Disk Utility v13 (426) that ships with 10.8 Mountain Lion. This is attached to a very cleanly installed Mid 2011 Mac Mini, which is acting as a media server. There is basically no 3rd party software on it, because it's acting as a NFS filer server for streaming digital players around the house.
However, I have the G-RAID set to spin down when possible in energy saver, and it's not. It never spins down. I have 4 external drives on this media server, ranging from USB to FW800 to the Thunderbolt drive, all from different manufacturers, and different sizes and models. All the other drives spin down after 10 minutes.
Not only is the checkbox "Put hard disks to sleep when possible" checked in Energy Saver, but a
pmset -g
reveals that the "disksleep" is set to 10 (min).
In frustration, I have tried a lot of things including (but not limited to) removing all other hard drives and hardware, starting up with shift held (safe boot) and removing any software at all that I thought would be keeping the drive "alive."
Finally I decided to start monitoring the drive with fs_usage, to see if I could suss out what is keeping this one drive alive.
"fs_usage | grep DISKNAME" reveals that SystemUIServer is accessing the drive every minute, about seven times in a clump. Considering that SystemUIServer is the peice of software that controls the little menu add-ons to the right of the menubar, I have spend a great deal of time trying to figure out what would use SystemUIServer that is accessing this drive.
Now it's true that this drive is set up as a time machine drive, but I have disabled time machine, and spotlight, and still I get the same SystemUIServer accesses every minute. Here is a fs_usage dump:
orion:~ seanb$ sudo fs_usage | grep Betelgeuse
Password:
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000029   SystemUIServ
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000011   SystemUIServ
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000017   SystemUIServ
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000010   SystemUIServ
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000008   SystemUIServ
15:53:16 getattrlist       /Volumes/Betelgeuse     0.000010   SystemUIServ
15:53:16 statfs64          /Volumes/Betelgeuse     0.000017   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000025   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000007   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000011   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000011   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000009   SystemUIServ
15:54:16 getattrlist       /Volumes/Betelgeuse     0.000010   SystemUIServ
15:54:17 statfs64          /Volumes/Betelgeuse     0.000014   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000062   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000013   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000024   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000010   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000009   SystemUIServ
15:55:17 getattrlist       /Volumes/Betelgeuse     0.000010   SystemUIServ
15:55:17 statfs64          /Volumes/Betelgeuse     0.000014   SystemUIServ
As you can see, it's the same seven drive accesses every minute. This is NOT occuring with any of my other drives. Now, here comes my wild conjecture. Is this something the system does because they are RAID slices? Do OS X software RAID slices check themselves every minute? This seems to be preventing them from sleeping.
Any help would be appreciated, I'm going nuts here.
Sean

The second column in your fs_usage report says that iStat Menus is what is accessing your disk (Istat64). Disable iStat Menus and I bet your issue will go away. I know there is a module in iStat Menus to monitor drive space, but if I recall correctly, even if that module is disabled, iStat has a habit of checking drives anyhow. I remember hearing people getting rid of istat menus in order to allow their HDs to sleep propely.
In fact, and easy way to test this would be to reboot your Mac with the shift key held down until you see your desktop load up. This will prevent 3rd party add-ons from loading like iStat Menus. Let me know if that works.
Unfortunatrly this is not the problem I am having, as I've booted with shift, and I still see the "getattrlist" accesses in my fs_usage report.
EDIT: stupid font made your report look like iStat when it was Lstat. So what I said about iStat Menus is probably incorrect. But using the shift key to boot could still lead you to the correct anwer. I'm doing testing on my end as well. Let you know if I see anything that pertains to your issue. (I got an Lstat entry in my fs_usage when I open the drive during testing, but I have not beeing getting them an regular intervals like you do. I would still guess that you have 3rd party software that is checking on drives periodically, and that holding shift might suss that out.)
Message was edited by: Cheule

How Can I spin down fans? I can't!

In kernel 2.6.23 times, without starting sensors or fancontrol daemons or any special module, only with laptop-mode-tools, fans were automatically spinned down when the laptop was "idle", not doing anything or only programming with vim.
After a few time, fans are never spinned down, generating unnecessary noise and spending battery. I have tried the wiki method for controlling fans described here: http://wiki.archlinux.org/index.php/Fan_speed_control but sensors only show this to me:
[root@helena david]# sensors
coretemp-isa-0000
Adapter: ISA adapter
Core 0: +28.0°C (crit = +85.0°C)
coretemp-isa-0001
Adapter: ISA adapter
Core 1: +28.0°C (crit = +85.0°C)
And pwmconfig tells me this:
/usr/sbin/pwmconfig: There are no pwm-capable sensor modules installed
I have searched the web and I found that there is a small bug in pwmconfig, but no more about how I can get fans spin down as before.
Anyone has a solution for me?
Greetings

here's kind of a 'cheesy' way to do it lol -
HERE

How to make a external HD (FireWire or USB) spin down when no in use?

I have a MM and want to make sure that the external HD spins down if not being used.
Would this automatically happen if I tick the box 'Put HD to sleep when not in use' in the control panel? Or is there an other solution to make sure it does so? I have not bought a disk as of now, but would be looking at a 2.5 (Samsung HM500LI 500 GB (SpinPoint M6)) in a FireWire housing.
Thanks

I really have no idea because I never sleep disks. However, that's controlled by the setting in the /Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist file. The default is ten minutes if you sleep disks. Experiment with various settings by issuing this command in the Terminal.app, until you get it the way you want it:
*sudo pmset -a disksleep XX*
where XX is the new time in minutes.

External firewire drive constant spin-down/up

I often connect an external Lacie firewire drive to my MacBook Pro for regular time machine backups. When the drive is connected and I'm using my Mac, the drive is constantly spinning and in an 'awake' state.
The drive remains in this state for as long as the display is on. As soon as the display enters sleep mode the external drive spins down, remains in sleep mode for 30 seconds, then spins-up for 20 seconds, only to enter sleep mode again. This cycle continues endlessly causing excessive noise and needless wear and tear.
I've unchecked put hard disk to sleep when possible in the energy saver preferences although this hasn't helped.
Any ideas?

Try un-checking the drive sleep box.
What model is the drive? Is it bus-powered or does it have its own AC power supply brick? What does LaCie have to say?

USB disk won't spin down

I tried asking this in the iMac forum, but as it seems to be a software issue, I hope you don't mind me posting it here:
I have a new iMac and a Lacie Blade Runner external 4TB USB 3.0 drive. Unfortunately when I power off the Mac, the Lacie keeps spinning and will not power down - very annoying.
Here's the strange thing though. When connected to my Mac Mini, the drive does power down properly when I shut the Mini down. (Both Macs are on 10.8.4). Also, when I power the iMac down in Bootcamp, the drive also spins down properly. So it does not appear to be a hardware issue.
I have "put the drives to sleep" (or whatever it is called) checked, btw.
Also, the disk will spin down if I put the iMac to sleep. It's only when I shutdown the iMac fully that the Lacie drive keeps spinning forever.
Any ideas how to get the external drive to power off properly when I shut down?

Is bumping allowed ;-)
Come on chaps - does no-one have any ideas? My drive is unusable if I have to keep turning it on and off all the time! How do I get an external USB drive to power off when I switch off my iMac? Surely there's something I can check?
My Mac Mini shuts it down just fine, but the iMac won't. Both on 10.8.4.
Any ideas?

Slow Shut Down Time For Macbook Pro Retina Snow Leapord

Hello, I was hoping somoene could help me with the following problems.
I have brand new Macbook Pro Retina, 15inch, 16G RAM, 500G of SSD, running Mountain Lion, and lots of professional recording software. My macbook frequently shuts down after 30 seconds, that wonderful grey wheel spinning in the center of the screen as if it were an old PC.
I've contacted apple frequently. They check to see that I've repaired disk permission, they reset...the RAM i believe, they ask if i shut down all the programs. Even through doing all of this, usually my macbook takes 30 seconds to shut down. Sometimes it takes only 5, which is how it usually should be. ANd this occurence seems to be inconsistent with the apps I use. Sometimes it takes long to shutdown when i've barely used a thing. Other times it shuts down immediately when i've used a lot of different programs at once. So there's no constant.
The apple boys suggest reformatting the computer to make sure it isn't a hardware issue. I refuse to accept that after only 3 months of use I already have to reformat everything. It's not the most enjoyable experience because I'd have to reinstal all my audio software despite Time Machine's magic tricks. Any suggestions?
Here is a link I've found on the matter: http://thecustomizewindows.com/2013/02/fix-mountain-lion-slow-shut-down-time/

These terminal commands decrease the excecution time of a process that has caused slow shutdown times for many users. This resolved my slow shutdowns. IF you are comfortable using terminal you can give them a shot, but be VERY careful using terminal.
These terminal commands should also fix the problem then and kill the services after 2 seconds:
Code:
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.coreservices.appleevents.plist sudo defaults write /System/Library/LaunchDaemons/com.apple.coreservices.appleevents ExitTimeOut -int 2 sudo launchctl load /System/Library/LaunchDaemons/com.apple.coreservices.appleevents.plist

CPU fan spins up for no reason and never spins down

I'm having problems with my new and otherwise immaculate iMac Intel 2.4 GHz. The CPU fan often spins up to 3500 rpm for no reason, even when left idle.
There are no processes running to justify the noise (no Spotlight indexing or anything) and the temperatures are as low as can be.
I have tried resetting PRAM and SMC many times to no avail.
Usually putting the Mac to sleep and waking it up slows the CPU fan down again, but it will go nuts at 3500 rpms sooner or later.
Once the fan has spun up to 3500 rpm it never spins down again unless the iMac is reset or put to sleep and woken up again. Even when hours of useless fan spinning has left it freezing cold.
SMCFancontrol won't help as it can't slow down fans only make them go faster.
Apple Support suggested I'd take it in for repairs but I'm reluctant as this smells like a Leopard/Boot Camp Issue from what I gathered on the boards. Also the repair service in Denmark is outsourced to third party repairers of questionable quality.
Any ideas?

I got my iMac back from repairs. They said they couldn't reproducere the error which might be as it at times appear very sporadic. The fans began to spin within the first day of use after I got it home though.
It seems that more and more users on the boards experience this problem. My theory now is that this must be a software issue as it usually begins once people update to Leopard 10.5.2.
The problem manifests itself like this:
The CPU-fan will start blowing at 3500 rpms for no reason (CPU-load and temperatures can be as low as can be.)
The CPU-fan will never slow down again by itself. Even after hours of unnecessesary spinning has left the Mac freezing cold.
Putting the iMac in sleep mode and waking it up again will temporarily slow down the CPU fan down to the usual 1200 rpms (usually for about 10 mins).
Resetting PRAM and/or NVRAM (SMC) will not help.
Installing SMCFancontrol will not help as it will only let you speed up the fans further - not slow them down.
So now I really hope Apple will address this problem with a new OS X release soon.
Still, if anyone manages to fix this problem with a hardware replacemnt please let us know.
Cheers, Jez

HD spin down time

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