I figured I better share this one, it drove me crazy for a while so maybe this will help someone. I picked up a fanless computer that had one PCI slot for a good price on e-bay-

Nexcom NISE 3100

My version works on 8 to 30 volts so I figured great I'll just slap a good sound card in the single PCI slot and I'll be all set. The problem is while some cheap soundcards worked, my Turtle Beach Santa Cruz and my X-Fi SB0770 didn't output any audio. It seems in their effort to make this thing work on 8 to 30 volts they decided not to feed negative 12 volts to the PCI slot.

I didn't think anything used -12 volts anymore but while looking at a data sheet for the X-Fi it stated that it needed -12 volts. While NEXCOM kind of sucks for not making the PCI slot fully functional, they did a least put a header on the motherboard to feed it -12 volts.

I ended up using a Texas Instruments PT6643P DC to DC converter to get -12v. I wired it in between the 8 to 30 volt input connector to the -12v in header. Now the X-Fi works. NEXCOM advertised this thing as having a standard PCI slot but not having -12 volts definitely does not meet the standard.

I wonder how many other of these small fanless low voltage motherboards are like this?