The Datapath Express9 backplanes use advanced PCI Express switches to create a high bandwidth fabric that connects up to nine PCI Express plug-in cards into a host system. The host can take the form of a Single Board Computer (SBC) which connects directly into the PICMG 1.3 system board slot of the Express9, creating a stand-alone 9 slot PC system. Alternatively a remote host can be connected into the Express9 backplane using Datapath's HLink-G3 and SLink-G3 products, transforming the Express9 into a 9 slot expansion backplane. Using multiple Express9 backplanes configured in expansion mode allows the construction of very large systems (up to 41 slots).

The Express9 backplanes provide nine 16-lane physical connectors, eight of which are electrically configured as 4-lane slots, and one of 8-lanes (slot 1). The 8-lane slot can be used normally, or can accept a Datapath HLink-G3 board to extend the PCI Express bus, over 8 lanes, onto a subsequent Express9 expansion board.

The Datapath Express9 uses PCIe 2.0 (Gen2) switching technology. The peak bandwidth available from the PICMG and slot 1 is 4GB/s and the peak bandwidth from slots 2 to 9 is 2GB/s. The PICMG and the 9 slots are all operating in bi-directional mode.

The Datapath Express9-G3 uses PCIe 3.0 (Gen3) switches to boost the data bandwidths to 4GB/s and 8GB/s respectively. Even when the Express9-G3 is expected to be used with plug in cards that are only Gen1 or Gen2 rated, the additional bandwidth can still be used to provide a peak bidirectional bandwidth between backplanes of 8GB/s (using the HLink-G3 and SLink-G3 board pair). When used in this way as part of a multi-chassis data wall system, for example, this link bandwidth eliminates the bottleneck between capture cards in one chassis and display cards in another chassis. As a guide, the 8GB/s bandwidth can handle approximately 14 full HD streams at 60Hz and 32bits per pixel in either direction.