display color banding issues (precision 7730/FHD panel)

I'm having color banding / washed out color issues with my precision 7730, the display runs at 6-bit instead of 8-bit as intended and the issue is really getting me frustrated. 

This used to happen when I use dell's premier color and I used to fix it by restoring color settings to original through intel command center, but it no longer works. 

I tried to reinstall Intel display drivers, use restore points and etc.

The images below could demonstrate what I mean, especially the first one, as it has it. The same image used doesn't appear to have any sort of banding issues on external monitor. The issue affects on the green color gradient the most. (I'm sorry if the images aren't clear enough)