Apple recently announced that 10.10.3 brought new support for 4K screens, mainly SST 4K support for the first time in 60 hertz. On their info website (https://support.apple.com/en-ca/HT202856 ) they say that: "Single-Stream (SST) displays With OS X Yosemite v10.10.3, most single-stream 4K (3840x2160) displays are supported at 60Hz operation on the following Mac computers: MacBook Pro (Retina, 13-inch, Early 2015) MacBook Pro (Retina, 15-inch, Mid 2014) Mac Pro (Late 2013) iMac (27-inch, Late 2013 and later) Mac mini (Late 2014) MacBook Air (Early 2015) MacBook (Retina, 12-inch, Early 2015)" and beneath that it says: "Multi-Stream Transport (MST) Displays These computers also support multi-stream transport (MST) displays at 60 Hz. MacBook Pro (Retina, 15-inch, Late 2013 and later) MacBook Pro (Retina, 13-inch, Early 2015) Mac Pro (Late 2013) iMac (Retina 5K, 27-inch, Late 2014)" But why doesn't the Late 2013 15" rMBP have SST 4K support when the Mid 2014 15" rMBP does? They have nearly identical components. What could be the reason for this? Or is it just a mistake?