Comment 3 for bug 835817

I not sure a bug report was ever filed on this specific issue, but here is the reference to the git commit which fixes this bug:

http://cgit.freedesktop.org/xorg/app/xrandr/commit/?id=27f86db064a5ea60b942fd3d3ddeb462d980df9b

It's easy to reproduce, for example:

  xrandr --newmode "640x480_75.00" 30.75 640 664 728 816 480 483 487 504 -hsync +vsync"
  xrandr

The output will be:
   ...
    640x480_75.00 (0x115) 30.0MHz
          h: width 640 start 664 end 728 total 816 skew 0 clock 36.8KHz
          v: height 480 start 483 end 487 total 504 clock 72.9Hz

Notice how the pixel clock freq. was truncated to 30.00 and the refresh rate is 72.9 instead of 75.0 like it should be.