Macbook Pro 15" mid 2012, external display @ 2560 x 1600 on 4K screen via DisplayPort? I have a Macbook Pro 15" mid 2012, and I want to add an external display running at 2560 x 1600. Given that I want a future proof display, I purchased a 4K monitor. (LG27UD88)

Of course I know it will not run 4K resolution, but I was hoping to would at least allow me to run 2560 x 1600 as supported by the NVIDIA GT650M.
Turns out I only achieve 1920 x 1080 :(

I connected with a purchased mini-DisplayPort to DisplayPort cable.
Could it be a limitation of the cable?
Will connecting via a mini-DP to HDMI cable change anything?

The 1920 x 1080 resolution is really superb and crispy, but it's a bit an expensive HD monitor...

Anyone any tips ?
Well looks like I found the answer to my problem.
All I had to do was press the Option button when selecting "Scaled" from the Displays setting; this allowed me to select 3840 x 2160 (30Hz) and 2560 x 1440 (60Hz)



Well, to be more precise, the 2560x1440 resolution is not 60Hz but for a weird reason it shows 59Hz in System Information. Does anyone know how come?