Example implementations relate to route demultiplexed signal pairs. In some examples, a motherboard of a computing device can include a chipset, a first Peripheral Component Interconnect Express (PCIe) bus, a second PCIe bus, a riser slot, and a demultiplexer connected to the chipset to selectively route particular signal pairs from the chipset to at least one of the first PCIe bus, the second PCIe bus, and the riser slot based on whether a riser card is connected to the riser slot.