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Would I still need purchase the temperature sensor? What else do I need? TIA!

If your system came with a blade SSD and you are replacing it with another blade SSD you don’t need a temp sensor iMac Intel 27" EMC 2546 Blade SSD Replacement If you are replacing the SATA HDD or installing a replacement SATA SSD instead of the blade SSD then you will need the thermal sensor iMac Intel 27" EMC 2546 Hard Drive Replacement here’s a kit with everything you need iMac Intel 27" (Late 2012-2019) SSD Upgrade Kit You might need a HD SATA cable if you are installing a new SATA SSD drive instead of the blade SSD iMac Intel 27" EMC 2546 SATA Cable Replacement