Adding Modelines to xorg.conf
If you experience problem with the Xorg resulutions maximum Hzs,
for example mine has supported max 1024x768@75Hz then you need to
generate Modelines and put them in your /etc/X11/xorg.conf, use the
gtf to do that. gtf - calculate VESA GTF mode lines. It worked for
hope this would work for you too.