21:9, 2560x1080 with AMD card
You can create mode resolution using xrandr
and gtf
First use gtf to create a mode line
gtf 2560 1080 60
this will generate something like this
# 2560x1080 @ 60.00 Hz (GTF) hsync: 67.08 kHz; pclk: 230.76 MHz
Modeline "2560x1080_60.00" 230.76 2560 2728 3000 3440 1080 1081 1084 1118 -HSync +Vsync
then create a new mode using xrandr and parameters from previous command
xrandr --newmode "2560x1080_60" 230.76 2560 2728 3000 3440 1080 1081 1084 1118 -HSync +Vsync
Now you need to add the mode to the desired output, in your case it seems to be HDMI-0
xrandr --addmode HDMI-0 2560x1080_60
Finally apply the new mode
xrandr --output HDMI-0 --mode 2560x1080_60
Cheers