StarTech.com 1 Port Low Profile Native RS232 PCI Express Serial Card with 16550 UART The PEX1S553LP PCI Express Serial Card turns a PCI Express slot into an RS232 (DB9) serial connection.The card is constructed using a native single chip design that lets you harness the full capability offered by PCI Express (PCIe) while reducing the load applied to the CPU by as much as 48% over conventional bridge chip serial cards.The PCI Express RS232 Serial Adapter Card is compatible with a broad range of operating systems including Windows® 2000/XP/2003/Vista™/Windows 7/Server 2008 R2 (32 and 64 bit) Linux Kernel 2.6.11 and up and ships with a low profile/half-height bracket installed but includes an optional full profile bracket that lets you add a serial port to virtually any computer (regardless of the case form factor)..