StarTech.com 2-port PCI Express PCIe to RS-232 Serial Cards - StarTech.com PEX2S553, The StarTech.com PEX2S553 PCI Express serial card lets you turn a PCI Express slot into 2 x RS-232 (DB9) serial ports. Based on a native single chip design (no bridge chip), this 2-port serial adaptor card allows you to harness the full capability offered by PCI Express (PCIe), and reduces the load applied to the CPU by as much as 48% over conventional serial cards. The RS-232 adaptor card is compatible with a broad range of operating systems including Windows, Linux Kernel 2.6.11 and up, and MAC OS 10.4 and above.Plus, the serial card includes a pair of optional half-height/low profile brackets that allow the card to be installed in any PCI Express slot, regardless of the size of the computer case.Backed by a StarTech.com Lifetime warranty and free lifetime technical support. StarTech.com PEX2S553 2 Port Dual Profile PCI-E RS-232 Serial Card