I recently bought a Dell U2518D monitor to use as my primary display paired with my 2015 Macbook pro 13". This is a 2560×1440 1440p monitor. I used the included display port to mini display port cable and the first thing I notice is the blurry fonts on full 1440p resolution.
I tried many things; using the EDID patch ruby script, using switchresx to create a custom resolution with double the 1440p resolution and setting this resolution as a hiDpi resolution, resetting NVRAM etc. Nothing seems to work. I even tried switching to an HDMI cable but it did not make any difference.
I have attached some images I took with my phone on what I mean by pixelated. Am I really supposed to see it this way? Am I imagining things and expecting too much after using the retina display for more than 3 years?
Edit: I am on El Capitan 10.11.6
Edit2: The monitor is display as a TV in System preferences. Screenshot below.
Best Answer
I also stumbled on the same issue on my MacBook Pro.
Default monitor comes with HDMI input source, so if you plug in an HDMI to thunderbolt the max you will get is 2048 x 1080.
All works well i.e. full 2560 x 1440 resolution if you use Displayport to Thunderbolt cable (which also comes along with the monitor), and also change the source using the monitor menu. I was quite amazed why Dell Support had no idea about this.
Resolutions can be confirmed using the below command.