Well I need assistance. As I have a late 2013 27” iMac. I was told that my sensor that controls my fan probably is gone and a logic board it needed. I want to know what all newer boards can I interchange with. Might as well upgrade if am going through all that work. I’ve changed 3 fans in my system and none same to turn on. I did a hardware test and it’s telling me my fan isn’t working, when I do the extended test, the computer eventually just shuts down. Any ideas on my next step.