The PCI Express link design of the Trenton BPG6600 backplane supports PICMG 1.3 graphics-class SHBs. The PCIe2 card slot connects directly to the SHB via a x16 PCI Express electrical link making it an ideal slot for high-end PCI Express graphics and video cards. PCIe1 is a x8 mechanical slot driven with a x4 electrical link delivered to the card slot via an IOB31 module installed on a Trenton TQ9 SHB. The 32-bit/33MHz PCI card slots are also connected directly to the SHB. The PCI-X slots connect to the SHB via a bridge chip that ensures secure data communications between high-speed PCI-X option cards and the SHB.