If you edit your /etc/X11/XF86Config file, make your 'Monitor' section look like this:
This should work on any modern monitor, however it may not work on some strange configurations. If it works you'll be able to change your resolution and refresh rate from KDE (Right click desktop -> Configure Desktop -> Display). If this fails you'll have to manually add your monitor details to this file.
As a note, the 'DPMS' setting allows power management on your monitor, you don't need it.