In 2015, Apple introduced the 21.5-inch iMac 4K with various upgrades that were passed to the iMac 5K, like new chipsets, SSD options, and the P3 color gamut. Also of note was the launch of Apple ...
Original story: A late-2014 display hooked to an early 2012 GPU The GPU powering the 27-inch iMac with Retina 5K display is the R9 M290X, with the R9 M295X offered as an optional upgrade.