okay, please help me! I dont know what kind of slots these are. I dont think they're pci, becasue i tried putting in a PCI USB 2.0 card, and it wouldnt fit. The same USB card fits in my powermac g4. I dont know much about pci-x so im not sure if its that. btw, my powermac g5 is the june 2004 1.8ghz, 4 RAM slots. Can someone please help me figure out which kinds of slots these are! thanks EDIT: If the slots are PCI-X is it backwards compatible with any other type of pci cards?