The new Intel based Mac Pro desktop computers, as well as the latest generation DualCore PowerMac G5's, have PCI-Express slots, and not PCI or PCI-X (Like the Delta/Revolution Series cards).  Not only are the data rates on PCI-Express different from PCI/PCI-X, but PCI-Express uses serial data transfers versus PCI/PCI-X transferring its data in a parallel fashion.  For these reasons, a PCI-Express type motherboard connector (or "slot") is physically different from a PCI or PCI-X type connector.  Therefore a PCI-Express adapter will not physically fit in a PCI or PCI-X slot, and vice-versa.  This is true regardless of the adapter card's manufacturer.

All of our current USB and FireWire interfaces are compatible with the new Intel Based Mac Pro and late model DualCore PowerMac G5 computers.