StarTech-com-4-port-PCI-Express-PCIe-RS-232-Serial-Adaptor-Card-StarTech-com-PEX4S553B-P-The-Startech-com-PEX4S553B-4-Port-PCI-Express-Serial-Card-lets-you-add-4x-RS-232-serial-ports-using-a-single-PCIe-expansion-slot-with-an-included-1-to-4-cable-enabling-you-to-add-4-serial-ports-to-a-single-low-profile-slot-The-serial-card-features-a-native-single-chip-design-that-provides-optimum-reliability-and-speed-reducing-the-CPU-load-by-up-to-48-over-conventional-bridge-chip-serial-cards-a-co