I would like to revive this thread, as I really like to know how to make two PCI cards work with D510MO.
RaymondDay, did you try with just one PCI card, in either PCI slot? I guess you are using a dual PCI riser card, which supposedly will only work with VIA motherboards, and it's possible that only one PCI slot will be enabled in the D510MO board. It's also possible that only the VIA or only the NEC card will work plugged in the riser card.
Could you be so kind to post the make and model of the riser card? Is there any model number printed on the riser card circuit board?