what does PCI-X mean

No, they are different designations for computer expansion buses. PCI-e is short for PCI Express bus. PCI-X stands for PCI Extended. PCI stands for Peripheral Component Interconnect. The two are not compatible, thus expansion cards such as a video card must be designed differently for each bus. An expansion card for a PCI-X bus will not work in a machine using the PCI-e bus.