This HDD came out of a Mid 2011 27" iMac with identifier 12,2. Has built-in temperature sensor connecting to iMac's SATA cable. Fan will spin loudly if using a incompatible HDD.

If seeking to install in < 2011 iMacs, will need temperature sensor solution. I will provide a transistor to insert into the sensor connector to the original HDD. See pic.

Please note Apple changed HDD temperature sensing mechanism nearly every year around this time frame. Best match to your 12,2 iMac with no separate temperature sensing cable and just built all into SATA interface.

Has El Capitan pre-loaded. Can't do higher as higher macOS such as High Sierra will also update iMac's firmware during installation so can't skip the installation sequence.

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