HPE 779098-001 PC Board - Primary PCIe riser board
Primary PCIe riser board - Has PCIe3 x16 full-height/half-length card socket (slot 1) on one side and PCIe3 x8 low-profile socket on the other (slot 2) - Plugs in the PCIe3 x16 slot on the system I/O board (center of the system I/O board)