Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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Replacing secondary hard drive, special cable needed?

The secondary hard drive a Hitachi 2 TB model is failing according to the SMART monitoring system.

I have read that 2011 iMacs need a special cable to deal with the heat sensor that was built into the Apple drives for that year. However I was told that my secondary drive DOES NOT need the special cable only the primary drive. True?

Do I need a special cable for my secondary HD on this iMac? My boot drive is the SSD that came from Apple.

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Dan -

Apple expected the 2nd SATA port would be used for a SSD which does not have the same level of heat as a HD would.

There is a spare sensor outlet on the logic board which you can wire in if you need to (that is if you are using a HD Vs SSD). In that case you will need to use the older sensor which is glued onto the HD case externally and then route the sensor cable over to the same location the other sensors are located.

Here's the IFIXIT guide to add in the second drive. Note a SSD is being used here. dual drive installation

Don't stop reading yet!

In your case the 2nd drive is the HD (as the SSD is the boot disk) so your main drive is failing and the sensor (2nd) is in fact the HD's not the SSD's.

Time for a new HD Sorry

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If the cable is not faulty you reuse it.

You might be confused, because as shipped, these models only supported the 3 Gb/s Serial ATA 2.0 standard for both a 3.5" hard drive and a 2.5" SSD. However, as first discovered by OWC, the iMac EFI Update 1.6, provides 6 Gb/s Serial ATA 3.0 support.

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I am not suggesting that the cable is faulty. That isn't the problem.

The hard drives for that model contained a sensor on the drive. Non-Apple drives do not have that sensor. That is why I am asking if a NEW cable with the sensor on it is needed.


The page linked (OWC) says: the most straightforward way to upgrade the hard drive is to "replace the drive with another model from the same manufacturer that [OWC or another third-party has] confirmed works properly with this thermal sensor cable". OWC provides a list of compatible drives. Readers have shared reports that taping an external temperature sensor to a hard drive or SSD that does not have an internal sensor will work in these models, but this method could be risky when data is important. I don't know who/where you were told you could use a drive that doesn't support the connector but I believe they are wrong.


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Dan Jurak will be eternally grateful.
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