If your video card/driver does not work out of the box, use a utility like PowerStrip to set custom timing.  PowerStrip is available here: http://www.entechtaiwan.com/ps.htm


QXGA @ 40Hz
Horizontal
      Refresh           61kHz
      Front Porch 24 pixels
      Sync        64 Pixels
      Back Porch  104 Pixels

Vertical
      Refresh           40 Hz
      Front Porch 1 Line
      Sync        2 Lines
      Back Porch  1 Line

Pixel Clock       137984 MHz




QXGA @ 46Hz
Horizontal
      Refresh           70kHz
      Front Porch 24 pixels
      Sync        64 Pixels
      Back Porch  104 Pixels

Vertical
      Refresh           46 Hz
      Front Porch 1 Line
      Sync        2 Lines
      Back Porch  1 Line

Pixel Clock       158681 MHz