Hello everyone!

I’m using a 4k 48" TV as a monitor, and want to scale the screen down to 3440x1440 / 21:9 with black bars on the top and bottom. I’ve managed to do this with the AMD Adrenaline software on my Windows partition, but when I tried to create a custom resolution on my EndeavourOS partition with xrandr, the screen just goes black whenever I apply it.

Has anyone here been succesful doing this, or have any tips? Thanks!