PCIe, PCIexpress is now the default video interface for the personal computer.

PCIe Bus Physical Interface Connectors

PCIexpress is used for are a number of different external interfaces

The electrical interface remains the same regardless of the change in its physical interface. Although regardless of the external interface, the PCIe interface remains the same.

The PCIe interface contains a large number of pin connections. Refer here for the signal assignments for the 1x PCIe connector. The page also has links to the 4x, 8x, and 16x PC Expansion boards.