You might be irked about this.
While the 2017 iMacs are getting good reviews, they’re currently unable to support Target Display Mode, a feature that previously allowed some iMac models between 2009 and 2014 to use their built-in display as an external monitor for another Mac connected via Mini Display Port or Thunderbolt.
Target Display Mode, which first debuted on the 2009 27-inch iMac, allowed users to turn an iMacs internal display into an external monitor, a feature some users felt would help prolong the life of the iMac after it went obsolete.
The feature was continued in the Mid-2010 refresh of the iMac, and then extended across the entire iMac lineup etween releases in Mid 2011 and Mid 2014. However, the feature was not supported in the Late 2014 5K iMac, apparently due to the fact that a single Thunderbolt 2 cable could not drive the full resolution of the new ultra high resolution display. No iMacs since have supported Target Display Mode.
At present, the newly-released 4K and 5K iMacs, both of which support Thunderbolt 3, do not have this feature. It’s also speculated that the Thunderbolt 3 protocol doesn’t have the bandwidth to drive a 5K (5120×2880) resolution, 10 bit display with 1 billion colors.
An Apple spokesperson has gone on record, stating that the 2017 iMacs are not designed to support Target Display Mode, and clarified that the feature is not planned to ever reappear. An Apple support page describing the feature, dated March 2017, also states that “iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can’t be used as Target Display Mode displays.”
While there are workarounds to emulate the Target Display Mode hardware trick, Apple appears to have nixed this for the long term.
Stay tuned for additional details as they become available.
Via AppleInsider and Apple