I'm using my DN2820FYKH as a HTPC. It's running Ubuntu 14.04 LTS (installed it last year).
Now I have a new projector and discovered that - for my needs - a video refresh rate of 50Hz instead of 60Hz is much better.
I can switch the refresh rate with the respective feature in Kodi. But I somehow can't set the default refresh rate to 50Hz!
With an xrandr Linux command I can set it to 50Hz at boot, yes; but when I have played a movie in Kodi and return to the desktop, it's at 60Hz again...
Is there any possibility to tell the Linux graphics driver to always stay at 50Hz, regardless what happens???
This is a very good question. My best recommendation is to post your questions in the Ubuntu Community so they can provide you with the command to accomplish this.
Here is their community: