StarTech.com 1-Port PCI Express Serial Card

Low Profile PCI-Express 16C950 Serial Card. The PEX1S952LP 1 Port Low Profile Native PCI Express RS232 Serial Adapter Card with 16950 UART adds an RS232 (DB9) Serial Port with data rates up to 460 Kbps to a computer through an available low profile PCIe slot, while relying on a native, single-chip design (Oxford OXPCIe952) that harnesses the capability of true PCI Express - ensuring maximum performance and reliability and reducing the load applied to the CPU by as much as 48% over conventional (bridge chip) serial cards.
The 1 port RS232 serial card features a half-height PCI Express mounting bracket that's designed specifically for low profile/small form factor computer cases, and includes an optional standard height bracket as well. Compatible with a broad range of operating systems including Windows and Linux for easy integration into mixed environments.