Comment 43 for bug 267241

All right so along the same lines, I have two Nvidia 7800 graphics cards on a SLI Bridge. I booted up and installed the Intrepid Ibex AMD64 live cd perfectly, it recognized, installed and rebooted using the Nvidia drivers. I started doing the Intrepid system updates and now it boots to a CL. when I login, I try to start x and it says the same as the OP:
...
Primary device is not PCI
(EE) No device detected.

Fatat server error:
no screens found
-- stopped for few seconds --
giving up.
xinit: Connection refused (errno 111): unable to connect to X server
xinit: No such process (errno 3): server error.

It says that verbatim, so I started trying what ya'll suggested (except using the i386 version, I can't). This is concerning because it worked off the live cd but an update prompted it to do this. I don't know what else to try. I know that:

You have 2 graphic cards and xorg doesn't know which one to choose as primary adapter. You need to define it in section "Device" of your xorg.conf config file with a line like:
BusID "PCI:02:00:00"

didnt't work for me so what's next?