When I connect my Macbook Pro to a 3840×2160 external monitor, the external monitor keeps going black and readjusting every 1-2 seconds. Some times it stops briefly, but the screen is just filled with green and pursple-ish colors, with the text "Use 3840×2160@60Hz for best result". I managed to take some pictures at the short breaks between constant readjusting and the text "No input source".
I checked which resolution the Macbook was trying to use for the external display, and it seems to be correct:
$ system_profiler SPDisplaysDataType | grep Resolution
Resolution: 2560 x 1600 Retina
Resolution: 3840 x 2160 @ 60 Hz
I have used the 4K screen a lot with a different PC and I know it works. I have admittedly not used the Macbook with an external display before, because I don't have the ability.
I have rebooted the Macbook, restarted the screen, reconnected the Mini-DP cable many times and tried using both Thunderbolt ports.
Has anybody seen something like this before, and could venture a guess as to what's wrong?
I'm using a brand new Macbook Pro retina 13" from 2015. The following is copied from its spec-sheet:
- 2,7 GHz dual core Intel Core i5, Turbo Boost up to 3,1 GHz
- 8 GB 1866 MHz LPDDR3 SDRAM
- 128 GB PCIe-based flash storage
- Intel Iris Graphics 6100
Best Answer
First thing I'd try would be a different cable.
Apple has this to say about non-compliant Display Port cabling, though not specifically in response to your particular issue, but Google brought me there whilst on that search...