If you have an iMac made in mid-2011 or later, here is how you can use it as an external monitor.

If you have need to connect a second monitor to your Mac and have a spare iMac lying around, here's how to use an iMac as a second monitor.

How to use an iMac as an external monitor New iMacs can use Universal Control, but or iMacs from 2009 to 2014 can be used as external monitors when running certain versions of macOS.

I have an iMac DV at 400Mhz and eventhough i dont plan to upgrade any time soon i am interested to know if i could use it as a second monitor when/if i will buy a tower.