Apple adds 5K support to MacBook Pro as target display mode remains absent for Retina iMac

The new 15-inch MacBook Pro has become the third Apple computer to ship with the ability to drive high-resolution 5K displays, but Apple's flagship 5K device — the iMac with Retina 5K display —  continues to lack the popular target display mode feature.

Apple revealed 5K support for the latest 15-inch MacBook Pro revision in a Thursday support document update. The company says its latest power-user laptop can drive Dell's UP2715K 27-inch 5K monitor when equipped with the optional AMD Radeon R9 M370X graphics chip.

Previously, only the latest Mac Pro and iMac with Retina 5K display were certified for use with that monitor, which remains the only 5K monitor Apple officially supports.

Meanwhile, Apple has yet to enable target display mode for its high-resolution iMac. This popular feature, which until now was present on all Mini DisplayPort-equipped iMacs, allows users to connect their iMac to another Apple computer and use it as though it were an external display.

There is no official word on why Apple has not added target display mode for the Retina iMac, but bandwidth restrictions imposed by DisplayPort 1.2 are a likely culprit. That situation may change this fall, when Intel's Skylake platform —  which ships with DisplayPort 1.3 —  is rumored to begin rolling out and will likely bring with it wider support for 5K displays throughout Apple's lineup.