Very difficult to work with these connectors.
Power cable very difficult to unplug - data cable veeeeery difficult to plug in.
I noticed that working with the iMac positioned vertically (and with a proper support for inclination) makes this step slightly easier…
I would strongly recommend using suction cups
I can confirm that replacing an Apple HD with a Seagate Barracuda (equivalent to the original) works fine, at least on my a iMac 27” late 2013 with Fusion Drive.
I know there’s mixed opinions about this, but in my case I didn’t need the OWC Temperature Adapter: I can see the temperature is monitored correctly and fans work as expected.
I just needed to open the iMac, replace the old Barracuda HDD, boot from USB, rebuild the Fusion Drive from Terminal, install Mojave and copy from backup.
Do not clone the HD if you have a Fusion Drive,: to create the new Fusion both SSD and HDD will be completely erased.
Apart from that, everything was pretty much streamline
Thank you so much for this guide: it would have been impossible otherwise!!!
I just did the same as you on a very same late 2013 27" iMac
I replaced the old HDD with a Seagate Barracuda (3TB newer generation) - but it looks like it doesn’t need the thermal sensor?
I booted on the new drive and the fans run on an average 1400, which is fairly normal I guess?
I also installed iStat and can clearly see that the HDD temperature is monitored! (30°C)
How did you notice that you actually needed a sensor? Did the fans just go mad?
Is there any other check I can do to see whether I need one or not too?
Thank you so much