Incorrectly sized fonts are generally caused by a monitor
reporting an incorrect physical size, which causes various X
applications to render fonts at the wrong size. You can check what
X thinks the physical size of your monitor is, by running:
xdpyinfo | grep dimensions
This will report the size in pixels, and in millimeters. If the
sizes in millimeters are drastically incorrect, then you can correct
this by adding the DisplaySize field to the monitor section of your
X config file (see the XF86Config or xorg.conf manpages for details).
You can check what your monitor reports its physical size is by
running X with verbose logging: `startx -- -logverbose`. Then,
search your X log file for a line that looks like:
(II) NVIDIA(0): Max H-Image Size [cm]: horiz.: 36 vert.: 27
(the numbers will be different) The NVIDIA driver uses these
values to compute the DPI.