This refers to the type of interface that the separate sound card plugs into the motherboard. PCI-E is 1X4X16X times faster transmission, but the interface length is also getting longer and longer, can not be mixed. Pci-e is a new generation interface type used to replace the PCI interface, but because the PCI interface has existed for a long time and has not completely withdrawn from the historical stage, many PCI sound cards are still retained on the surface. At present, the new generation of independent sound cards generally use PCI-E4X or 1x interface.