can an old iMac be used primarily as an extra monitor if so please explain and thank you
I have an old iMac , say 2012 or so. can I use it as an external monitor?
iMac Line (2012 and Later)
Question marked as
iMac's are all-in-one computers, not displays for other devices.
There is a feature called Target Display Mode where a qualifying iMac could be used as a display for another qualifying Mac, but it is limited to only certain year models and macOS's.
please carefully study > Use your iMac as a display with target display mode - Apple Support