I had a problem when I moved my Raspberry Pi over to using a 4K display, which is just about the only resolution that professional displays come in these days, as manufacturers have all moved on to 4K as a standard. The problem was with overscanning and the display not having the ability to correctly scale the image signal coming from the Raspberry Pi, which was still a 1920x1080 signal.
There's a collection of settings in
config.txt on the Raspberry Pi that can mitigate this problem:
For me, I deleted all the explicit overscan settings, and enabled the
Here's my fixed up
More settings and info can be found here: https://www.opentechguides.com/how-to/article/raspberry-pi/28/raspi-display-setting.html