or do they all cause it individually?
It is only fwohci+ehci card that doesn't work with the card that I have.
Just a wild guess; some "BIOS" (preboot program to enumerate PCI device and prepare various PCI matters for real OS) fail to cope with "two-functions-in-a-single" cards which equip two PCI device chips. Lately most of PC BIOS do well the job smart, however it's likely a case where old RISC firmware fails the similar way, I suspect. Toru Nishimura/ALKYL Technology