The pcix1pex4 pci x to x4 pci express adapter lets you install a low profilehalf height x4 pci express card into a full height pci x 33v 64 bit slot on a server or other high end motherboardr r with a physical x16 pci express female slot connector the pci x to pcie adapter card accepts all types of x16x8x4x1 physical pci express cards maximum speed of x4 allowing an older system to run the newest cardsr r backed by a startechcom 2 year warranty and free lifetime technical support