Complex sentence: PCI-X was needed as some devices, most notably Gigabit Ethernet cards, Fibre Channel and Ultra320 SCSI controllers, and cluster interconnects could, by themselves, saturate the full bandwidth (only 133 MB/s) of the PCI bus.
Split into simpler sentences: PCI-X was needed as some devices, most notably Gigabit Ethernet cards, Fibre Channel and Ultra320 SCSI controllers. These devices, as well as cluster interconnects could, by themselves, saturate the full bandwidth (only 133 MB/s) of the PCI bus.