PCI Express is the newest technology for computer expansion cards and is superior to both PCI and AGP, in terms of graphic performance. PCI Express connections can support fast data transfer rates, which can be used to connect high-speed devices such as graphics cards. The slots come in different variations and speeds, such as x1, x4, x8, and x16. Although x4 and x8 links are also available, x1 and x16 are the most popular for personal computers. Presently most of the available motherboards come with PCI express slots. To use a PCI Express x1 graphics card, your computer must have at least one free PCI Express slot..