Hi All.

Can someone pls help clarify the firmware situation for me pls? I have a 27 inch 5K late 2014 iMac and the 3TB fusion drive has failed.

I have managed to determine that the conventional drive is the part at fault and I want to change it, but I am reading about custom firmware's. Is this true? or am I able to just swap out for a new "off the shelf" Western Digital 3TB drive?

If it is true about the firmware how do I get a compatible drive and how do i install the custom firmware.

If I buy an identical drive to the 3TB Seagate drive, Can i just swap over the circuit board from the dead drive? Would that contain the custom firmware?

Thank you for any advise you can offer.