Hi Adrian,
Yes, you can place the Decklink HD card in the top slot and the PCI-X apple fiber card in the lower slot (it will run at 100mhz) and it will still give you plenty of throughput.
Shane Sokolosky
SAN Product Manager
ProMax Systems inc.
16 Technology Dr. Ste.106
Irvine, CA. 92618
Office (949) 727-3977 x108
Toll free (877) 776-6292
Fax (949) 727-7002
Website-
http://www.Promax.com
shane.sokolosky@promax.com