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Re: Xproblem - modelines [try a different IRQ]

Earlier this week there was a discussion of trying to get an S3
graphics card to work with XFree86 and getting only black screens
after startx.

I had reported that some people said that S3 cards and LX motherboards
didn't mix. I had given up on this combination, though I didn't
understand why this particular S3 card worked in one of my
LX motherboards but not the other.

I even bought a new-used Matrox Millennium to substitute for the
S3 card, and mysteriously that -too- gave only black screens, even
though it worked on the other LX.

Then I figured out the issue:

  On the working LX box, the BIOS assigned the video card to IRQ
  11, as IRQ 9 was taken by a modem.

  On the black-screen LX box, IRQ 9 was free, and the BIOS assigned
  IRQ 9 to the video card.

  In the BIOS setup, I forced IRQ 9 to be unavailable for PnP, and
  the video card got IRQ 11. Presto! The Matrox Millennium now
  works! (Presumably the S3 card probably would too.)

Perhaps this is due to the special treatment IRQ 9 sometimes gets
for VGA purposes (something I don't really understand.)

So if you are getting black screens and your card is using IRQ 9,
try forcing to to something else.

Dan Halbert

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