M31 Series Monitor + Wie-Ya Chassis = Composite Sync Problem... Help!

[MonkeyJug]

I have a Big Century cabinet, with the monitor and chassis as listed above.  Actually, the chassis is a 3126DB.

My problem is up until now, I've been using XP 64-bit as my OS.  I now want to switch to using GroovyMame Linux distro.

In Windows, the picture would constantly roll vertically and no amount of v-hold would get it to become stable.  I figured out that I needed to tick the 'Composite Sync' box in the ATI CCC, and as soon as it was ticked, the picture snapped into place, perfectly.

Now, I am at a loss as to how to get it to stop rolling now that I am attempting to use Linux.  I am reading about joining wires together to create Composite Sync, but I'm hoping someone in here has had a similar problem and can advise me on how to go about rectifying this...

I have a J-Pac, but I would rather bypass that altogether, as I have been doing in XP, by connecting the monitor VGA straight to the graphics card (HD4350), via a DVI connector...

Any help welcome!!