If you are sure that your video setup on that Linux PC supports a higher resolution such as 1200x1024, you could use xrandr
's newmode
to manually add that resolution as described here: https://wiki.archlinux.org/index.php/Xrandr#Adding_undetected_resolutions
First determine the modeline using cvt
$ cvt 1200 1024
# 1200x1024 59.82 Hz (CVT) hsync: 63.59 kHz; pclk: 101.75 MHz
Modeline "1200x1024_60.00" 101.75 1200 1280 1400 1600 1024 1027 1037 1063 -hsync +vsync
Create a new mode in xrandr based on that output:
xrandr --newmode "1200x1024_60.00" 101.75 1200 1280 1400 1600 1024 1027 1037 1063 -hsync +vsync
Add that new mode to your current output:
xrandr --addmode VGA1 1200x1024_60.00
Then switch to the new resolution:
xrandr --output VGA1 --mode 1200x1024_60.00
The authors of that wiki smartly suggest adding an automatic fallback mode following a five second delay, in case the new resolution totally borks your setup:
xrandr --output VGA1 --mode 1200x1024_60.00 && sleep 5 && xrandr --newmode "1024x768-safe" 65.00 1024 1048 1184 1344 768 771 777 806 -HSync -VSync && xrandr --addmode VGA1 1024x768-safe && xrandr --output VGA1 --mode 1024x768-safe