I'm trying to set up a dual-head system (SSE + SI), but it's not
working properly. What happens is that the primary board is not being
seen by the system at all when the secondary board is present - the
secondary is the only working display. The secondary is also the only
board that shows up in hinv or gfxinfo.

The dual-head installation guide talks about a software CD, but this
is all used stuff so I don't have that CD. I also haven't been able
to find said software online. According to the diagnostic procedures
in the guide, it's a hardware problem with the primary board. But
that doesn't seem right to me as the primary board works fine when
it's the only board.

Can anyone provide any clues or pointers?