Viewsonic VP2330wb wide display

[dsavage at peaknet.net]

I recently purchased a SuperMicro dual Opteron motherboard with an
on-board ATI ES1000 video chipset capable of 1600x1200x24. I'm having
little success hooking it up with a Viewsonic VP2330wb display that wants
-- very much it seems -- to display 1920x1200.

system-config-display detects the ET1000 and applies the radeon driver.
The monitor is not in the ViewSonic list, so I select the generic "LCD
Panel 1920x1200". The generic LCD and ViewSonic have different sync rates:

              LCD Panel 1920x1200     ViewSonic VP2330wb
HorizSync     31.5 - 90.0             24.0 - 96.0
VertSync      59.9 - 60.1             50.0 - 85.0

I've manually edited /etc/X11/xorg.conf to insert the ViewSonic's numbers.
But no matter what set of numbers I use, I am unable to get the monitor to
display any higher resolutions than 1280x1024, and even then it appears in
a smaller virtual window with a 4:3 aspect ratio. I have tried all three
of the monitor's three Scaling options: Fill All, Fill Aspect Ratio, and
1:1.

The monitor periodically complains it is not being driven at 1920x1200,
but at resultions higher than 1280x1024 the monitor complains "Out of
Range". To access resolutions higher than 1680x1050 I backed down from
Millions of Colors to Thousands of Colors (depth = 16).

I have been unable to hit on any combination of mode, scaling, sync, or
depth to get a 1920x1200 display. I'm just about at my wits end.
Suggestions?

--Doc Savage
  Fairview Heights, IL

P.S. Please don't suggest an add-in video board. This is a very new server
motherboard. Its only video option is a small black PCI-Extended x8 slot,
and I'm not aware of any video boards available with a PCI-e/x8 interface.