This HDD came out of a 2011 iMac. 2011s use built-in temperature sensor inside HDD 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. Beaware of the necessary temperature solution. Even without hardware modifications, using a free program call Macs Fan Control and reduce fan noise once program is launched (for example, auto launched after login)
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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