Why is this resolution "inaccessible"?

[Peter Jay Salzman]

Hi all,

On my system, lspci reports:

   0000:00:02.0 VGA compatible controller: Intel Corporation 82865G
      Integrated Graphics Controller (rev 02)

And I use the i810 driver:

   Section "Device"
      Identifier   "Intel Corporation 82865G Integrated Graphics Device"
      Driver       "i810"
   EndSection

Here is the screen section:

   Section "Screen"

   Identifier  "Default Screen"
   Device       "Intel Corporation 82865G Integrated Graphics Device"
   Monitor      "Generic Monitor"
   DefaultDepth 24

   SubSection "Display"
   Depth 24
   Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480" "320x200"
   EndSubSection

   SubSection "Display"
   Depth 16
   Modes "320x240" "800x600" "1280x1024" "1024x768" "1280x960" "800x600"
   #Virtual 1024 768
   EndSubSection

   EndSection


There are certain modes, like 320x200 and 320x240, that I would really like
to use, but the X server reports they're unusable:

   (1152x864,Generic Monitor) mode clock 100000MHz exceeds DDC maximum 140MHz
   (320x200,Generic Monitor) mode clock 100000MHz exceeds DDC maximum 140MHz
   (1600x1200,Generic Monitor) mode clock 162MHz exceeds DDC maximum 140MHz

How is it possible that 320x200 needs a dotclock of 100 GHz?  How can I get
320x200 (and 320x240) to be available modes for my system?

My resolution is normally 1280x1024.  How can I not run 320x200?

Thanks!
Pete