Chosen Solution

I have a 1tb firecuda st1000lx015 laying around and I want to put it in my iMac, either replacing the current HDD or in place of the SuperDrive. I’ve a read online that I might need a temperature sensor…thoughts?

Yes, to prevent racing hard drive fan, you will need the OWC thermal sensor. https://eshop.macsales.com/item/OWC/DIDI