Custom mode

If your monitor requires a mode that is not in one of the tables above, then it's possible to define a custom CVT mode for it instead:

***please note, need to ad a blank space before the bracket, in order to display it here correctly***
hdmi_cvt=< width> < height> < framerate> < aspect> < margins> < interlace> < rb>

Value 	Default 	Description
width 	(required) 	width in pixels
height 	(required) 	height in pixels
framerate 	(required) 	framerate in Hz
aspect 	3 	aspect ratio 1=4:3, 2=14:9, 3=16:9, 4=5:4, 5=16:10, 6=15:9
margins 	0 	0=margins disabled, 1=margins enabled
interlace 	0 	0=progressive, 1=interlaced
rb 	0 	0=normal, 1=reduced blanking

Fields at the end can be omitted to use the default values.

Note that this simply creates the mode (group 2 mode 87). In order to make the Pi use this by default, you must add some additional settings. For example, the following selects an 800 × 480 resolution and enables audio drive:

hdmi_cvt=800 480 60 6
hdmi_group=2
hdmi_mode=87
hdmi_drive=2

This may not work if your monitor does not support standard CVT timings.

pm2 stop

via SSH
and try to change the resolution manually on the running Linux.
(Maybe you can add temporarily a mouse to the pi or log in remotely via VNC)
VNC can be enabled via SSH within the console (sudo raspi-config)