Sometimes even the best educated guesses can be thrown for a loop when an unforeseen “X-Factor” comes into play. Such is the case with the Late 2009 iMacs.
As we were getting information together for the new iMac instructional videos, we came across a little tidbit that, apparently, hasn’t been covered anywhere else: Apple has switched the iMac’s method of hard drive temperature sensing. They’ve gone from an external sensor that attached to the outside surface of the drive to a connector that seems to use the drive’s internal sensors.
On first blush, this would appear to be a good thing; an internal sensor is closer to the drive’s mechanics and is likely to be more accurate regarding drive state. Unfortunately, there are no industry standards regarding the ports/pins used to access this information, and each hard drive manufacturer seems to do it their own way. And more unfortunately, when the iMac gets no sensor information via that cable, the heat exhaust fans kick into permanent high gear, so that cable must be connected.
That means, in order to upgrade the internal drive, you need to have a connector cable that’s compatible with the brand of drive that you’re installing… and that’s an Apple service part not generally available to the end user. Pretty sneaky, Apple!
Fortunately, you can reuse the cable that came with your iMac as long as you replace the drive with another model from the same manufacturer we have confirmed works properly with this thermal sensor cable. To determine what brand hard drive your iMac has, go to About This Mac, click on Serial-ATA, and then look for the drive model installed at the factory. If the model has the preface WD, that’s a Western Digital hard drive and if your drive has a ST, that’s a Seagate hard drive. Once you know what drive came with your Mac, you can upgrade to a larger drive and continue to use the thermal sensor…thus avoiding the “ear pleasing” whoosh of fans on high.
Here’s a list of the drives that install into WD factory equipped iMacs:
- 1.0TB Western Digital Caviar Black
- 1.0TB Western Digital Caviar Green
- 1.5TB Western Digital Caviar Green
- 2.0TB Western Digital Caviar Green
For the Seagate equipped models, these drives from us will plug right into the thermal cable:
Fortunately, upgrading memory is still easy to do, and will show a more immediate improvement in performance than will a hard drive upgrade. That doesn’t mean, though, that somewhere down the road you won’t want to upgrade your hard drive to something larger and/or faster.
We’re all about giving you the most options for upgrading your Mac and that’s why OWC is looking into potential ways to turn this curveball from Apple into a Home Run for you. As soon as we can find a viable method for connecting a different brand hard drive than the one that came with your 2009 iMac, you can be sure you’ll hear it first right here on the OWC Blog.
In the meantime, if you get stuck for storage, you can always take advantage of that lone FireWire 800 port (or, if necessary, one of those USB 2.0 ports) and add a fast external storage device, such as the Mercury Elite-AL Pro. The benefit of this is that when you are able to upgrade that internal drive to your preference, you will have a handy extra external unit for backing up to.
Keep tuned to the OWC Blog for updates…
Loud Fan Problem – SOLVED – COMFIRMED..!!!!!!!
Hello guy’s .. i just upgraded my hard drive on my 27″ iMac from a 1TB to a 2TB..( Seagate )… and as you would expect.. i ran into the the loud fan issue where it starts slow and then goes full blast and stays that way. Well as “Diesel87″ posted in this page..he performed a wire trick where he swaps the grey wire to the black wire and vise versa. This absolutely worked !!!!!!! I no longer have a loud fan anymore and everything is back to normal..!! I check it with the iStat application for mac and it gets the correct thermal temperture and fan speed for the hard drive. Im so glad i stumbled into this page cause it truely fixed my loud fan issue!! if you have this problem do the wire trick..though you might need some small pliers and patience..but it pays off..!
Thanks and i hope this helps..!!
- Katra
Do anyone know if the cabletrick is usefull in a late 2009 imac 21,5 ???
Or have anyone testet the cable in the 21,5 model…?
Can someone please confirm for me this? If my Late2009 27 inch Seagate died, repalcing it with a WD Green HD will require a new cable. I found this cable: https://www.usedmac.com/products/922-9225-imac-27-western-digital-hard-drive-temp-sensor-cable
Issue that I can see is buying this cable doesn’t mean it will work right either. Sorry to sound lame but I’m getting confused messages. Do I need the cable AND software fix or will just the cable make my “Seagate” iMac work with a WD Green drive?
I replaced my late 2009 imac with another seagate HD (not a model listed). but i can verify that replacing the with the same model doesnt necessarily mean that the sensor is still going to work..going to try the 922-9229 Optical Temp Sensor Cable route…
btw if you want to go the software route…. HDD control fan did work instantly…
@Takeabiteofapples Same here I have 10.1 late 2009 27′ and bought what OWC stated as correct one but temp sensor does not seem to work properly. Did you already try the temp sensor cable? IMHO that is the best solution rather then software one.
I have a late 09 imac. Want to replace the current seagate drive in it with a seagate 3tb drive ST33000651AS. Will this work? Please let me know.
I’ve got a problem with my 1TB HD ST31000528ASQ in my 27″ iMac (late 2009).
Is it correct that when i buy a 1TB HD from Seagate –> ST31000528AS AND the 922-9229 Optical Temp Sensor Cable that i won’t have any problems with my fan?
I mean, when i buy the Optical Temp Sensor Cable do i also need the Apple customer firmware?
I asked a Apple store over here and the OEM HD would cost me 286,90 Euro OMG !!
This is so confusing – I read somewhere else that as long as you buy the correct model ST31000528AS (as this post suggests) it has the correct firmware (AP24) – but others are suggesting it doesn’t? Or are we just talking about people who are switching brands?
If I order the replacement ST31000528AS – will it work without hacking the temperature sensor. So a like for like replacement.
As an aside If you send it to an authorised repairer, what do they do – order the Apple branded drives from Apple? How much more do they cost!?
the cost of HDD from apple is extortionate.
If you buy the replacement drive from OWC you will need to buy HDD Fan Control to correct the runaway fan issue.
It works.
And the way I look at it, $70 for the drive from OWC and $30 for the software, you’re still way ahead of the game.
The Apple Store will replace the hard drive for $200-$300 ( no apple care – and they wouldn’t give me an exact quote), the one local Apple Authorized Service place (Mac Specialists, Virginia Beach) wanted $500 to do it.
Seems like a rip-off to me, Apple should either make the firmware available or not use it.
Was your replacement a WD or Seagate.
It’s supposed to be plug & play if you make the exact replacement/size upgrade listed in the article.
Here is the solution:
Apple installs custom firmware on their hard drives. So even if you order one of the temperature sensors mentioned above, your fans are still going to be running at full blast. (And if you take your iMac to an Apple Authorized Service Provider, it will fail all of their testing)
You can install an optical drive temperature sensor cable from previous generation iMacs. This attaches to the hard drive like older iMacs did (to the top with a piece of tape basically). Now your iMac will be able to correctly read the temperature of the hard drive, causing the fans to run normally. And, when running Apple Service Diagnostics and the Apple Service Toolkit at an AASP, it will pass all the testing.
The part you need to order is: 922-9229 Cable, Temp Sensor, Optical. Its cheap.
I have used this cable on an iMac (21.5-inch, Mid 2010) and it works great. Though, I haven’t tried it yet on other models yet, it should work just the same.
Good luck!
Hey Guys,
I´ve got THE solution for replacing the standard HDD with an WesternDigital Drive.
First you need the named WD-adapter(Part No. 593-1062). The trick is: You have to put the adapter invert onto the Jumper-Interface so the grey cable is connected to Jumper-Pin4 and the black cable to Jumper-Pin3.
When you´ve got an iMac with an WD drive the adapter is connected grey on Pin3 and black on Pin4. Thats all.
The lenght does´nt matter. Only the right direction ist important. I´ve done an mistake when I ordered the adapter, so I got an adapter for the 21″ iMac. But it works also…
So good luck with replacing your HDDs with WD drives.
After all I can only advise you to use WD drives. At my work I had in two years about 7 failed HDDs – All of them where Seagates… So decide the maufacturer your own. In my oppinion WD is the better choice…
Have a nice day
sorry, I forgot to post the HDD I´ve used.
Its an WD10EARS. This one have the needed temp sensor.
Just wondering if this worked perfectly or did you still need a fan control app on your iMac?
Thanks
Here is the solution:
Apple installs customer firmware on their hard drives. So even if you order one of the temperature sensors mentioned above, your fans are still going to be running at full blast. (And if you take your iMac to an Apple Authorized Service Provider, it will fail all of their testing)
You can install an optical drive temperature sensor cable from previous generation iMacs. This attaches to the hard drive like older iMacs did (to the top with a piece of tape basically). Now your iMac will be able to correctly read the temperature of the hard drive, causing the fans to run normally. And, when running Apple Service Diagnostics and the Apple Service Toolkit at an AASP, it will pass all the testing.
The part you need to order is: 922-9229 Cable, Temp Sensor, Optical. Its cheap.
I have used this cable on an iMac (21.5-inch, Mid 2010) and it works great. Though, I haven’t tried it yet on other models yet, it should work just the same.
Good luck!
I have 27″ 2.66MHz i5 iMac with the HDD fan operating at 4200RPM. I have upgraded to a 2TB Seagate Barracuda XT drive (Seagate 1TB was originally installed). I notice that since the last SMC firmware update my HDD fan has been blasting away, also the battery status being reported for the wireless mouse and keyboard in control panels is inaccurate. It is reporting 100% for the mouse when the actual is 56% (reported by iStat Pro) I am using rechargeable batteries and I know they never report 100% even when fully charged. And the keyboard status also is incorrect.
I am quickly coming to the conclusion there is a SMC firmware issue affecting various 27″ iMac’s.
svenc: thanks for sharing, your swap wire trick worked for my 27″ iMac too. I swapped the failing stock Seagate 1T for a new Seagate 2T. Even though the heat senor plug is identical the fan keep blasting at 5000rpm and iStat Pro returned “–” for the HDD temperature.
I swapped the two wires of the plug (see svenc’s post above) with the help or a paperclip, and it now worked. Fan spinning at 1133rpm and I get normal reading from iStat on the HDD.
Hi Scott, could you please share some photo? I have one 2.5 inch HDD, it also come from my MacBook. I want to do same.
JuNK @ post #107, you are a genius. I bought a new 1.5 TB WD Green to replace the thunk thunk thunk of the 1 TB Seagate that came with my Mid 2010 quad core iMac. Sure enough, different connector for the thermal. Thank God I read through far enough to see your post…I grabbed an older 160 GB 2.5 inch Seagate that came with a MacBook, slapped that on top of my new drive courtesy of some cushiony double-sided tape, and plugged the thermal cable into the old Seagate. Everything fit perfectly, no problems, and the new drive works with NO FAN ISSUE WHATSOEVER. In fact, the fans spin up normally when they need to (I am using SuperDuper to copy the old drive to the new…heavy work) and have only gotten to 1400 before spinning back down normally.
Thanks again for your find. You are my hero.
I’m a bit late in the game but our offices just received five 2009 model 27 iMacs. I’m planning to purchase a few OWC Mercury SSD to replace the hard disk. May I ask how difficult is the switch? Or probably it would be more advisable to simply keep the 1 tb drive and buy the iMac data doubler and replace the ODD?
Hi Tintin, I don’t know about seagate, because my 1TB HDD is using WD. It only 2 pins.
Thanks everyone for their inputs. I’ve recently changed my Seagate 1T with a Seagate 1.5T. The 4pin sensor socket fits the original cable but probably due to the firmware the logic board is not picking up the signal. The HD fan blasts at 4500 rpm.
I’ve tried the commandline code with smcFancControl app and it works like magic, though it was said that you have to run everyone after your mac sleeps.
http://discussions.apple.com/thread.jspa?threadID=2528945&tstart=0
Franky, can you share how to DIY the 2n3904 temp sensor? I heard it’s shorting the Base and Collector – but then connect which end to which pin (seagate connector is 4 pin)?
Tom Yanckowitch, could you please share your’s ?
@ Tom
Please share the command line code – I have a 2TB WD with HDD fans at their max (mid 2010 27″ i7)
Torstein you have really done your homework. Thanks for this input. So now I know that because I managed to spin down HD vent to 1100 rpm I can be still safe from any overheating.
Yes I said it!! I found fix and made my crazy fan go down! I used smcFanControll app and a comand line in Terminal.
It works as magic! I am happy there was no need for some service guy poking around my mac!
I think it’s safe to short the temperature connector, even for regular hard drives (non SSD). Because it takes real abuse to make the hard drive fan speed increase. In practice, hard drive fan speeds over 1100 rpm isn’t necessary.
I’ve reached this conclusion after extensive testing of a 27″ Core i7 late 2009 iMac, and a 21″ Core i3 mid 2010 iMac. With a stock (Apple branded) 1 tb Seagate Barracuda 7200.12 drive inside both computers, and the machines under heavy, continous load for several hours, the CPU fan went faster but the hard drive fan was just hovering around 1100 all the time. Like it would have done, had I shortened the temp wire. I used TemperatureMonitor to watch the temperatures, and SMCFanControl to watch the fan speeds.
What I did was this: I duplicated lots of files, making the hard drive work intensely for hours, and at the same time repeatedly converted a HD movie (from iso file) to .mp4 with Handbrake, totally maxing out all the CPU cores. The temperature of the hard drive was 49 degrees celsius at the most for the 27 inch and 53 degrees for the 21 inch. Room temperature was normal, 23-24 degrees celsius.
To see if maybe the CPU fan was cooling also the hard drive, I eventually ended the Handbrake conversion process, just keeping the file duplication going, and the CPU fan spun down to normal speed, but the hard drive fan did not spin up. I waited an hour to see if it changed speed, but nothing happened.
To find out what would happen in a really hot environment I placed the 27″ iMac on the radiator in my living room to see if the warmer conditions there had an impact. I took the temperature right outside the middle of the screen, and it was 37 degrees celsius. I did the same test as described above, and the CPU fan went higher this time (almost 3000 rpm) but the hard drive fan was again just hovering around 1100 rpm. Temperature on the hard drive reached 55 degrees.
However, on the next day, after the iMac had sat on top of the radiator the entire night, I tried again, and this time the temperature reached 58 degrees, which triggered the hard drive fan. The fan went from 1100 rpm to 1300 rpm. I couldn’t get the temperature higher than that, even after several hours, and when I ended the Handbrake conversion, the hard drive fan went back to 1100 rpm, with the file duplication still going strong.
I bought the Hitachi Deskstar 7K3000 3tb disk and installed it in the 27″ iMac, then tried the test again (on the floor, not on the radiator). This disk is both warmer and noisier than the stock Seagate Barracuda 7200.12. It reached a max temperature of 63 degrees, and the seek noise was more obvious (but it’s still pretty quiet behind the iMac’s screen).
My conclusion is that for light and moderate use of your iMac, you can safely buy and install any hard drive. Short the temp wire, you’re not gonna need it. For really heavy use it’s safest to go with disks that is not hotter than the stock Seagate Barracuda 7200.12. At the temperature this disk generates, and below, the fan never spins up anyway. But if you want a hotter disk, you can argue that even if you shorten the disk’s life a bit when you constantly run it hot, the speed you gain make this tradeoff rational. You can always use an external Time Machine backup disk, then you’re safe, no matter what.
Yesterday 14 feb.2011 i got delivered brand new 27″ Imac 2010 i5. Afeter 10 min. into using it I noticed fans and air stream from the back that was unusual for idle iMac.
I came across tis site and read Petes post that describes my problem too! Once booted the fan will begin running at ~ 2500 RPM. It will continue to increase in speed until it reached very near max speed….. not quiet.
Running hardware diagnostics generates error 4SNS/1/40000000:TH00-9.000
Serial ATA check informed me that I have !!!SAMSUNG!!!! HD !! and that is in original factory sealed and delivered mac!
What can I do about this? I cant stand the fans!!!!
I got faulty iMac on arrival. Apple said they would service it but I am not excited on a machine that needs service upon its first boot up!!!
27″ Imac 2010 i7, anyone used the Seagate Hdd 2Tb 64mb cache ST32000641AS 7200rpm. for upgrade?
Any problems with fan speed?
Original HDD is 1tb seagate ST31000528ASQ
What about the 2tb firmware? Any problems with fan speed on new drive?
Tha sensor cable connector is the same, but don’t know about firmware.
Thanks
Found this on the Apple discussion board. It basically confirms that Apple has a special firmware on Seagate drives. It is not 100% sure that this firmware make standard drives unusable (because of the fan problem) but it seems like it:
“I bought HDD ST31000528AS for my iMac, but without correct Firmware AP24, it is not work correct in my iMac. Please give me a link for ISO disc with firmware AP24.
My HDD is working, but without AP24 firmware iMac can not get correct thermo data from jumper connection. That is why fans going to fly away…
[...]
Got reply from Seagate. About Apple’s HDD and firmware AP24.
Thank you for contacting Seagate in writing.
The firmware is only available from Apple. It is specific firmware they have made available for the drives to work with their system. You will need to contact Apple about this problem.”
http://discussions.apple.com/thread.jspa?messageID=13053887
2011.2.4
According to a post on today’s Macintouch Apple forum, all you need is the correct temp sensor cable, which can easily be ordered on the Net.
*** quote
Flat-panel iMacs used to have a temperature sensor attached to the hard drive. Without this sensor attached the fans will run full as they have no way of knowing whether they actually need to be cooling or not, and therefore err on the side of safety. Newer hard drives have the temperature sensor built in to the hard drives themselves. Each manufacturer is free to use any pin configuration they choose. If you change the brand of hard disk you simply need to order the correct temperature sensor cable for the new drive. If you use a manufacturer that Apple doesn’t use then you need to wire the cable yourself.
Apple use the following 3 brands:
Hitachi (hard drive sensor cable Apple part number 922-9223)
Seagate (hard drive sensor cable Apple part number 922-9224
Western Digital (hard drive sensor cable Apple part number 922-9225)
***unquote
AppleComponents.com has the Hitachi cable for US$19.
Is the true fix as simple as this? No proprietary firmware involved or sensor machinations involved?
Hi Fred,
I read your post about the Hitachi sensor cable and used it in my iMac with a 3TB Hitachi drive. It will NOT fix the problem with hard spinning fans. When the imac is cold the fans start spinning at 2500 rpm gradually increasing to 5500. HD temp is only 43 C. Please send me a link to the original Apple post. There is got to be a fix.
Thanks