Will taking out the HDD portion of a Fusion Drive in an iMac cause the fan to continuously spin?

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Will taking out the HDD portion of a Fusion Drive in an iMac cause the fan to continuously spin?

I know that replacing the HDD with a Non-Apple HDD will cause the fan to spin continuously due to the temperature sensor not being connected. My question is, if you take the entire HDD drive out, including the cables; will it still cause this issue or will the logic board automatically detect that there is no HDD, hence no need for the HDD temperature sensor?

I am planning on taking out the entire fusion drive (HDD and SSD portion) and replacing it with just a higher capacity SSD blade module, and I just wanted to know if taking out the HDD will cause the same issue as replacing the HDD.

iMac with Retina 5K display, iOS 11.4.1

Posted on Sep 24, 2018 7:56 PM

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Answer 1

Top-ranking reply

Resurrtronics Author

Level 1

18 points

Sep 27, 2018 7:19 PM in response to samtenor

Thanks for the replies guys. To answer my own question, I just took out my HDD and SATA cables. Also replaced the SSD portion with a Samsung 970 Pro using an 12+16 M.2 SSD adapter. It runs perfectly. I am getting 2000MB/s read/write and 3000MB/s read speeds.

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Answer 2

samtenor

Level 4

2,074 points

Sep 25, 2018 3:02 AM in response to Resurrtronics

For what I have experience regarding DIY upgrade. After 2012 (including 2012) iMac models (21.5 or 27) that NO inline-sensor is needed when replacing HDD. This also seemed to be applied to fusion drive models by just replacing HDD to SSD (rebuild the fusion drive, or use the SATA 3 drive as main boot drive).

However, there are few would stated the need of inline-sensor. Your own risk if you proceed the process.

The cable has nothing to do with the fan issues, the temp sensor was built in within the HDD circuit (so apple can ”seal” with propriety hardware - which were notorious in 2009 2010 and 2011 models if HDD fails).

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Answer 3

babowa

Level 9

78,580 points

Sep 24, 2018 8:41 PM in response to Resurrtronics

If you don't get any answers here (I have never seen a question like this here), I suggest you also post over at ifixit.com - they are the disassemble/re-assemble guys.

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Will taking out the HDD portion of a Fusion Drive in an iMac cause the fan to continuously spin?

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