The next generation of the PCI slot. Currently, PCI-E is being used for high end video cards. It's serial data transmission scheme accelerates the data transmission of those add-in cards using it.
PCI-E is suitable for SATA Hard Drive Controller Cards and other Add-in cards that requrie a large amount of bandwidth.
PCI-E can emulate the old PCI enumeration protocol.
PCI-E is a new transmission standard for high-end graphics cards.