I asked a similar question a few weeks back and since then I have been ordering more and more cables to resolve this issue and I'm about another day away from tossing the crap in the bin.
I decided to upgrade from my Ryzen 2200g with intergrated vegas graphics to a Rx 580 gb for a bit more of a gaming boost.
I disabled the integrated and moved all my display cables from the Mobo display outputs to the Rx580 outputs.
This should be a simple move across from using the Mobo display outputs to the RX580 display outs but it isn't!
So the problem is I have one monitor that has a 75hz refresh rate and I had it set as this for over a year when using the 2200g....
The moment I moved over to the rx580 I've never been able to go above 60hz.
And I have no idea why this can even be happening both the 2200g and RX580 use the same Radeon Software... i'm using the exact same cable and everything is identical in everyway.
The only thing as mentioned that's changed is the wire was moved from dvi output on mobo to dvi output on gfx card,
ANYONE know how to resolve this without suggesting reinstalling windows.... reinstalling graphics card.... etc.. the usual auto responses.