FC3 won't boot unless monitor is off - s3 unichrome/Ilyama Vision Master Pro 410

[huwevans]

Hi all and thanks in advance for any help

I'm having trouble with an Iliamya Vision Master Pro 410 monitor on a machine with the following spec:
Asus A7V400-mx motherboard / Athlon XP processor / 512mb ram
The onboard vga is an S3 unichrome
No add-on hardware, only on-board (vga/audio/ethernet etc)
It is a fresh installation of FC3, updated via yum.

It seems bizarre, but I can only boot up into X while the monitor is turned off.
If I attempt to boot up with the monitor on, I get this message:

I cannot start the X server. It is likely that it is not set up correctly.
Would you like to view the X server output to diagnose the problem?

The error messages I get are as follows:

(EE) VIA(0): No valid modes found

Fatal server errors:
Caught signal 11. Server aborting

XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0" after 0 requests (0 known processed) with 0 events remaining)

Here are the (I hope) relevant parts of my xorg.conf file:

Section "ServerLayout"
Identifier "single head configuration"
Screen 0 "Screen0" 0 0
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection

Section "Module"
Load "dbe"
Load "extmod"
Load "fbdevhw"
Load "glx"
Load "record"
Load "freetype"
Load "type1"
Load "dri"
EndSection

Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Iiyama A702HT, VisionMaster Pro 410"
DisplaySize 320 240
HorizSync 27.0 - 96.0
VertRefresh 50.0 - 160.0
Option "dpms"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "via"
VendorName "Videocard vendor"
BoardName "S3 UniChrome"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 16
Modes "800x600" "640x480"
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
Modes "1400x1050" "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
EndSection

Section "DRI"
Group 0
Mode 0666
EndSection

I am running at 1400x1050 screen resolution. If the monitor is off when I boot up, everything is ok, sometimes when I log out it is also ok, but sometime it fails to go back to the graphical log-in screen and I get this error:

mtrr: MTRR 3 not used

and it goes back to the "I cannot start the X server...." dialogue.

I am utterly confused! I don't know whether it is an issue with the video card or monitor or both, or something I've done wrong. I haven't been using Linux for that long so please bear this in mind.

Thanks.

[AndyGreen]

Hmm, this is DDC probing. DDC is how the monitor is meant to be able to explain its capabilities in terms of refresh rates and so on, but some monitors have "crazy DDC" that doesn't seem to work.

There is an X driver option to disable ddc...
http://xfree86.org/4.4.0/via.4.html

Option "NoDDCValue" "boolean"
Disable the use of DDC to set the horizontal sync and vertical refresh.

stick this in your Device section.

[huwevans]

Thanks Andy for your extremely fast response!
Tried that but still no go I'm afraid.

[huwevans]

Ok, it does work! I was being stupid - I took it literally and put in the "boolean" part.
As soon as I deleted that it worked.
Thanks Andy