How To Fix Your Monitor Refresh Rate In Debain

The easiest way I have found is to use the ‘gtf’ command. The syntax of the command is:

gtf Horizontal Vertical RefreshRate
so if you wanted a screen resolution of 1024×768 with a 100 hz refresh rate the command would be:

gtf 1024 768 100

and the command will show you a line something like this:
# 1024×768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHzModeline “1024×768_100.00? 113.31 1024 1096 1208 1392 768 769 772 814 -HSync +Vsync

Now you need to copy this to the monitor section of the /etc/X11/XF86Config-4
so that it would look something like:

Section “Monitor”
Identifier “Generic Monitor”
Option “DPMS”

# 1024×768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHzModeline “1024×768_100.00? 113.31 1024 1096 1208 1392 768 769 772 814 -HSync +Vsync

EndSection

Save the changes and restart the xserver for the changes to take effect.