I'm relatively new to Linux, and I don't know much about tweaking it. For a while now I've been casually fighting with getting dual heads to work in Fedora (first in Fedora Core 7, then in Fedora 8). Every time I tried enabling dual, a change would be made somewhere that would make it utterly impossible to start up the computer all the way. It would get through POST, GRUB & most of system start, but both monitors would immediately shut off when X started, and stay off. Even more annoying, this change persisted even after I shut down & unplugged one of the monitors. I would have to reinstall the OS to fix it (An intelligent, knowledgeable person would have simply backed up xorg.conf, then restored it in recovery mode, but I didn't know where it was yet.)

I asked about how to get things to work here on the boards a couple of times after I could not find anything on google, but nothing anyone suggested would get things working properly. I basically gave up for a couple of months, but took up the fight again today.

I finally got around to finding the X configuration file (/etc/X11/xorg.conf, go figure) and took a look at it before and after, and realized that the problem was that when I enabled the second monitor, it would only partially define it. It would put some of the information on the second video card entry in, but not all of it, and would not connect it in any way with the second display. I rewrote the xorg.conf file using what was present in both the functional single head and non-functional dual head versions of the file as a reference.

The following is completely functional in my box, which uses a matching pair of Samsung Syncmaster 930B's connected to a single GeForce 6600:
I didn't save what it looked like originally, but it only had maybe two thirds of the information present in this version.

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