Is it possible to convert an Intel iMac to an external monitor for a new iMac?
Yes, but only if the older iMac is a 27-inch iMac, which Apple’s only been shipping a few years. With any other iMac you’re out of luck, but these 27-inch models have a unique feature: they can be used as an external monitor for another Mac. Simply plug in a male-to-male Mini DisplayPort (or Thunderbolt) cable into your iMac, and the other end into any flavor of Mac that supports Mini DisplayPort or Thunderbolt. Mini DisplayPort cables are slightly cheaper than Thunderbolt cables at this point, and will be able to power a display without any issues.
Thunderbolt cables can be used alongside regular Mini DisplayPort cables for powering displays.
That’s it: just plug it in, and your iMac will work as an external display. You can tweak the settings of the display (screen resolution, arrangement, and so on) under System Preferences > Displays, just as you would with any other external monitor.
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ctx83
November 08, 2011 at 11:53am
Some statements in this article are misleading.
According to Apple, the thunderbolt equipped iMac will ONLY work with a thunderbolt to thunderbolt cable, and ONLY with another thunderbolt computer. A computer that has mini dp instead of thunderbolt, or using a mini dp cable with 2 thunderbolt computers will NOT work.
For more info see: support.apple.com/kb/TS3775
marcmartineau
November 08, 2011 at 2:32pm
Yep ! ctx83 is right ! I have a MacBook Air 2011 latest revision with Thunderbolt and an iMac 27 inches 2010 with MiniDisplay Port. According to a genius at the Apple Store Genius Bar, I would have been able to use the 27 inches 2010 iMac as a second display with my Mac Book Air 2011 with a Thunderbolt cable...
Well, after spending 56$, it does not work ! A complete waste of money ! I don't have any devices that uses Thunderbolt cable so the cable is useless !
bitshifter
November 04, 2011 at 1:53pm
Don't you need to press command-F2 to toggle Target Display mode on the iMac that is to be used as a monitor?
Also, I think any of the newest generation of Thunderbolt equipped iMacs can be used in Target Display mode if the source is also a Thunderbolt equipped Mac.
