I recently upgraded my computer and learned enough about modelines that might be of help.
The modeline I’m using for the Benq G2222hdh monitor is:
Modeline "1920x1080_60.00" 148.5 1920 2008 2052 2200 1080 1108 1113 1125 -hsync +vsync
I couldn’t use xvidtune as I got an “unable to query monitor information” error. So I manually adjusted it using the two numbers immediately following the horizontal and vertical refresh rates. i.e. 2008, 2052 and 1108 1113. The numbers in each set were increased by the same amount, eg. 2011 2055, restarting Xorg in between each adjustment, to check, so that I got them in a position I was happy with.
If you need a modeline for your max resolution then open up the Xorg log:
vim /var/log/Xorg.0.log
Somewhere you will find a line beginning:
h_active:
This line the one immediately preceding and the one following it contain the numbers you need for the modeline. Mine looked like this:
[ 7343.008] (II) RADEON(0): clock: 148.5 MHz Image Size: 477 x 268 mm
[ 7343.008] (II) RADEON(0): h_active: 1920 h_sync: 2008 h_sync_end 2052 h_blank_end 2200 h_border: 0
[ 7343.008] (II) RADEON(0): v_active: 1080 v_sync: 1084 v_sync_end 1089 v_blanking: 1125 v_border: 0
Ignore h/v_border and Image Size. The modeline of the above output would be:
Modeline "1920x1080_60.00" 148.5 1920 2008 2052 2200 1080 1084 1089 1125 -hsync +vsync
Figuring it out from here is trivial.
