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 2000xp2003vista windows 7server 2008 r