I have a new 2015 15" Retina Macbook Pro with the AMD Radeon R9 M370X graphics card. I also have a Monoprice 28 in UHD LED 4K 60Hz monitor with DisplayPort input, with a native resolution of 3840x2160/60 Hz. The rMBP drives this monitor wonderfully at 3840x2160/60 Hz with a DisplayPort 1.2 to mini-DisplayPort cable. My question is, can my rMBP drive a second identical monitor at the same resolution and frame rate? In other words, can it drive dual 3840x2160/60 Hz monitors, if each is connected to one of the two Thunderbolt ports? Apple's tech specs page for the 2015 15" rMBP is unclear on the matter. It says: Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on up to two external displays, both at millions of colors But it doesn't say whether it can do them both at 60 hz. Has anyone tried this yet? I'd like to know before I order a second monitor! Thanks!