I recently bought a Dell U2518D monitor to use as my primary display paired with my 2015 Macbook pro 13". This is a 2560x1440 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.