If any reader has a logical explanation and/or solution for this, please post your answer.Ĭan I do with my early 2015 MacBook Pro Retina? This result has persisted despite restarting my Mac but I do not know if this behavior is limited to my example. The refresh rate on the 4K screen is dropped to 30 Hz if it's one of only two active displays. To sum up, this means that my early 2015 rMBP 13' will only display 4K 60 Hz on the screen capable of doing so if either all 3 displays are active or the 4K display is the only active display. Scenario 3 = 2 desktops without builtin screen:ĭisplay 1 (old) is connected with 900x1440 60 Hz,ĭisplay 2 (4K) is connected with 3840x2160 60 Hz Scenario 2 = 2 desktops with builtin screen:ĭisplay 2 (4K) is connected with 3840x2160 only 30 Hz RMBP Early 2015 with macOS 10.12.6 and 16 GB RAM ĭisplay 1 (old): 900x1440 via mDP-DVI adaptor and DVI cable Display 2 (4K): 3840x2160 via mDP-DP cableĭisplay 2 (4K) is the only desktop displayed at 3840x2160 Hz Also, MacOS does not let me choose the refresh rate for the 4K screen when it's connected through the Mini DisplayPort to DisplayPort cable - other than feeling the difference, I only see the refresh rate in the system profiler. However, there are anomalies on my side when it comes to the refresh rate depending on my screen setup. I have a similar device (Early 2015 rMBP with 16 GB running macOS Sierra 10.12.6) and can confirm that it will power an external 4K display at 60 Hz - it's supposed to power two external displays at 4K (3840x2160) in addition to the builtin display, in fact.

Early 2015 macbook pro used