[CentOS] Problems with widescreen (16:9) under CentOS 5 w/ xorg-x11-drv-i810-1.6.5-9.40.el5

Robert Heller heller at deepsoft.com
Sat Sep 22 17:55:57 EDT 2012

I am the tech guy for a local library.  We have a network containing
several diskless workstations.  The hardware are these P4 boxes:


(We have inserted additional memory, bringing most of the machines up to
1.25Gig of memory, and two up to 2Gig of memory.)

These little machines have integrated Intel video chips on their
motherboards and have both VGA and DVI connectors:

(II) I810(0): VESA VBE OEM Vendor: Intel Corporation
(II) I810(0): VESA VBE OEM Product: Intel(r)845G/845GL/845GE/845GV Graphics Controller
(II) I810(0): VESA VBE OEM Product Rev: Hardware Version 0.0
(II) I810(0): Integrated Graphics Chipset: Intel(R) 845G
(--) I810(0): Chipset: "845G"

And the i810 driver seems to be happy to talk to these chips.

I am using the stock (distro supplied) RPM: 


The machines are running pretty much stock CentOS 5.8 (I am slightly
behind on some updates).

These machine boot off the network and then mount their root (/), /usr,
and /home file systems via NFS from the server and function otherwise
as normal workstations.  And they work great with 4:3 monitors. 
Recently, because of new cataloging and circulation software which
seems to have been designed by (open source) developers who probably
have new widescreen monitors on their machines, we have put widescreen
(16:9) monitors on three of the machines (various menus and toolbars
don't fit on a 4:3 monitor, even at 1280x1024 [19-20" monitor]).  But
we are having some problems getting the proper aspect ratio (or even a
display at all) on two of the three.

First of all, using the VGA connection, the X server *refuses* to use
any Modeline that is not a 4:3 aspect ratio.  It seems that the X
server presumes that *all* VGA connected monitors are 4:3.  (All three
of the new wide screen monitors do have 15-pin VGA connections, so this
'presumption' is obviously false, esp. since the monitors using DDC
while connection via VGA are suggesting 16:9 mode lines.)

I got *one* of the machines to correctly use a 16:9 aspect ratio
Modeline (1600x900) using the DVI connection.  The other two don't
work. One won't display anything (claims that the video is missing or
wrong). And the other just uses something like 640x480.  Both monitors
work just fine on DVI in console display mode (bare kernel VGA), so the
video card is seeing the monitor and sending it a signal at that level.

I have tried everything I can think of.

The various log files and config files are here (each tar file contains
one log and one config):

This is the *working* machine (HP W2072a):


These are for a (not working) Acer X223W:


>From xdpyinfo while connection via VGA:
screen #0:
  dimensions:    1680x1200 pixels (474x302 millimeters)
  resolution:    90x101 dots per inch

And for a (not working) ViewSonic VA2431WM:


>From xdpyinfo while connection via VGA:
screen #0:
  dimensions:    1600x1200 pixels (521x290 millimeters)
  resolution:    78x105 dots per inch

We would really like square pixels -- is it possible or not?

Robert Heller             -- 978-544-6933 / heller at deepsoft.com
Deepwoods Software        -- http://www.deepsoft.com/
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