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iMac Intel 27" EMC 2309 (Late 2009, Core 2 Duo 3.06 or 3.33 GHz) ID iMac10,1, EMC 2374 (Late 2009, Core i5 2.66 GHz or Core i7 2.8 GHz) ID iMac11,1

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Replace HDD Temperature Sensor Cable with correct brand?

I have a 2009 iMac Core i7 2.8 GHz upgraded with an SSD in place of the optical drive and 32 GB of RAM. All that works great, however I have had the Seagate 1 TB drive that came with the iMac replaced under Apple's extended replacement program. This second Seagate drive has also failed, and surprisingly I'm eligible for another free HDD replacement (even almost 4 years later). Of course I do not want another small 1 TB Seagate HDD (that may fail again) installed, and be without my iMac for a couple of days.

Instead I have already installed a Western Digital Black 4TB HDD. I have read many discussions and possible solutions to switching brands because of the different connectors for the temperature connector. But I couldn't find anyone that suggests or confirms that I can just buy the appropriate cable for the different brand HDD. I found this on eBay: Temp Sensor Hard Drive Cable 922-9225

Is there any reason I can't simply replace the Seagate temperature cable with the Western Digital temperature cable? Are the internal sensors in the different brand HDDs actually different therefore the SMC won't recognize the signal and adjust the fan speed appropriately? (This would suggest that firmware or the logic boards are different for each brand of HDD, I find that doubtful.)

Simply replacing this cable seems like the perfect and simple solution because it has the correct connector to the hard drive.

(If buying the correct cable won't work, then what is the best software fan control solution?)

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Hi Gatorpk

Did this solution work for you - I guess you've had time to test it by now - or would you in hindsight not recommend this route?

Many thanks



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Soluzione Prescelta

Your correct all you need to do is swap out the cable harness with the correct cable for your new HD (Seagate for Western Digital). But before doing that why don't you get your system to Apple to get the HD anyways. Then take it out and put it into a case to use as a backup drive or even sell it. Free is good ;-}

Here's the rundown of the different temp cables:

  • 922-9223 - Hitachi
  • 922-9224 - Seagate
  • 922-9225 - Western Digital

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Thank you Dan!

The 4TB WD Black HDD that I installed appears to be defective anyway (since it can't format correctly, and I found a dent in the plastic corner near the SATA connector, but decided that it is probably fine, I guess I was wrong, perhaps G-shock damage). The fan is hanging around 4800 RPM. With all this new info, I was considering just buying a slower, cheaper 4TB 5900 RPM Seagate locally and putting that in so I wouldn't worry about the fan speeds and save my self about $110 overall ($80 cheaper HDD + $30 cable) and two more weeks without a HDD to make a nice Fusion drive with.

Because of your comment, I'm shipping the defective 4TB WD HDD for exchange, and I am in discussions with Apple Authorized Dealers in the area that will hand over a replacement Seagate HDD, and save themselves the trouble of installing it. Some local places aren't being nice about it, some I'm waiting to hear back from the service department.

Thanks again!



No problem ;-} If this answer answered your question please remember to rate (score) and mark it accepted.


I had already scored this now Accepted Answer, didn't see the "Accept Answer" link. I have used this site many times for research and the repair manuals. I have even contributed to this site. Though I've only asked two questions ever on this site. I keep forgetting the power of asking for help. I should make a habit of this because both questions have been answered incredibly well and also helps other people researching the same thing. Thank you for your help, and your advise about rating and accepting questions. (It should be obvious to me!)


I also wanted to mention an update about getting Apple to replace my 2nd faulty 1TB Seagate hard drive. The first representative was incorrect about my eligibility to get another replacement. The first replacement itself would only have a 90 day/1 year warranty on parts and/or labor. (I forgot which was which). The replacement hard drive lasted me since January, 2011. So 3.5 years I suppose isn't terrible, but I think a HDD should last the life of the computer. That is another reason I decided to stick with the Western Digital Black 4TB HDD, it comes with a 5 year warranty, instead of a 2 year warranty that a 4TB Seagate drive has. I believe the warranty itself states the confidence a company has in their product. This is going in a 2009 iMac, it should last the rest of it's life. However, it seems this nearly 5 year old Mac will be the best Vintage (defined 5 years old) Mac I've ever owned. It has a Core i7 Quad-core with 32 GB of RAM and will have a fast Fusion drive with OS X 10.10 Yosemite.


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Using the external cable is unlikely to work correctly on a non- iMac specific drive, and it even has to be for the correct series iMac.

The generic drives usually do not have the correct firmware to use Apple's temp cable.

In the case of WD drives, the late 2009 iMac repurposes pin #5 on the jumper block for temp data.

On a generic WD drive, pin #5 floats at about 2.5 v. If it is shorted to pin #6, (ground, 0 v) the drive is set for SATA 150 mode.

On a WD Blue drive pulled from a late 2009 iMac, pin #5 floats at 2.5v, and carries a 2-pulse signal every 4 seconds. Presumably, this either carries the temperature data, or is some kind of handshake.

An Apple-branded WD drive pulled from a 2007 iMac lacks this signal, as do the new generic WD drives I tested.

Apple's 2-wire cable connects pins #5 (signal) and #6 (ground) to the logic board. If the cable is jumpered, the logic board goes to low fan. If open, or if the correct signal is not present, it goes to high fan.

So, if you attach the WD temp cable upside down, as suggested elsewhere, you disable fan control and set the drive for SATA 150 mode!

Fortunately, OWC offers an external temperature sensor that mimics the correct signals from the iMac-specific drive. This allows use of non-Apple drives, including SSDs in the main drive bay.

It's possible that an Apple optical drive temp sensor, which is taped in place, could work, as they do have the same logic board connector. It does not appear to be a simple thermistor. I have not checked the function of this. Perhaps someone could hook a scope up to one in a working system and see. The part number for a 2009 iMac optical drive temp sensor is: 593-1152

Why would Apple do such a thing? It's better, and cheaper too, from their point of view. The drive's internal sensor is more accurate than the older taped-on sensor, and not using the data stream to read temp data prevents slowing down the system. Serviceability and upgradeability with non-Apple parts has never been a top priority for Apple, as the machines are meant to be repaired by Apple and replaced when obsolete.

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Hi Keri - You clearly have had some fun with the different setups Apple has used over the years. If you keep the idea of different generations (Gen1, Gen2 & Gen3) I think it would simplify things.

The first generation with a stuck on thermal sensor is a no brainer as long as you don't forget to take it off the drive and put on what ever drive you are planning on using.

The 2nd generation drives which use the internal thermal sensor are more confusing! If you get the correct series of drive you can follow what I had posted here, But as you have noted some drive makers have changed things! Some of the current drives have dropped functions we need like SATA speed adjustment (SATA II in this series) as well as a header to plug in the thermal cable into (and wired for it). In the case of a SSD you'll need to forge an external thermal sensor out of the optical drives sensor (not very good) or use the OWC adapter cable for this series (I don't like using software overrides as I've seen to many burnt out systems from using it). Frankly, finding a fixed SATA II SSD's that meet my needs (1TB) almost impossible as everyone is now making fixed SATA III drives.

The current 3rd generation drives as you have noted use an internal sensor with Apples custom firmware on the drive. If you don't get a drive with the needed firmware you will need the OWC adapter cable for this series.

Try to keep the focus on the series as you will confuse people. Trust me I've over done it a few times my self ;-} Adding a second comment post for a rant works too. Hope to see more posts from you.

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Dan, I'd appreciate some advice: My late 2009 iMac has been opened for a video graphics bake (successfully!), but for some odd reason the Hdd temp sensor cable has vanished and now needs to be replaced. Should I try to find out which HDD-brand my Mac has and get the matching cable or might I just as well replace it by the owc thermal sensor solution and thus be prepared for a coming HDD/SSD-upgrade? Thanks for an answer,



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