There is a problem with the fans on the iMac (2012's and on) once a HDD is replaced with a non 'Apple' HDD, i.e. the Fans turn on to high speed when power is of or in sleep mode. I may have accidentally found a fix (all the reset procedures have not worked for me).
System Preferences, Energy Saver:
Computer sleep slide - NEVER
Display sleep slide - NEVER
tic HDD to sleep
tic wake up for network...
tic power nap...
Then leave the computer on without any interaction until the screen goes into a "screen saver mode" (thats sounds a bit strange that because you have selected NEVER).
And that fixed it for me! Been running like it should ever since.
Strange.
System Preferences, Energy Saver:
Computer sleep slide - NEVER
Display sleep slide - NEVER
tic HDD to sleep
tic wake up for network...
tic power nap...
Then leave the computer on without any interaction until the screen goes into a "screen saver mode" (thats sounds a bit strange that because you have selected NEVER).
And that fixed it for me! Been running like it should ever since.
Strange.
