It would be helpful to install the Intel HD Graphics driver. This link will tell you how to do exactly that:
http://www.noobslab.com/2014/03/intel-graphics-installer-helps-you-to.html
You should also install
vaapi from this page:
https://launchpad.net/ubuntu/+source/intel-vaapi-driver
...or this page as your hardware requires:
https://packages.debian.org/wheezy/libva-intel-vaapi-driver
You should also have installed
CompizConfig and
CompizConfig Settings Manager from the Software Center or the command-line.
It might also be helpful to look at this information:
Setting resolution changes in xorg.conf
If the file is not there, you can create it.
Notice how to append the refresh rate:
Section "Monitor"
Identifier "External DVI"
Modeline "1280x1024_60.00" 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
Option "PreferredMode" "1280x1024_60.00"
...with an underscore and 60.00 like so "
_60.00". That value can be modified.