TABLE OF CONTENTS One of the great things about PCI Express interconnects is their flexibility and versatility. By taking advantage of the inherent features of PCI Express architecture and signaling, a system designer can easily incorporate PCI Express links into a variety of different topologies. This section presents some of the more common topologies or uses of PCI Express interconnects in a system environment.
As PCI Express becomes more prevalent in the marketplace, it is likely to be used more and more to connect the various components on a system board together. Figure 5.1 presents an example of connections between two I/O hubs on a desktop system board. In server systems, however, backplane connections become prevalent and the chip-to-chip interconnect is made through connector interfaces as well as across the system board.
As a high-bandwidth replacement for AGP graphics cards, PCI Express interconnects are likely to be implemented with a x16 link width and connector size. In ATX or micro-ATX form factors, for example, a PCI Express graphics port is likely to interface with Slot 7, shown with the x16 connector in Figure 5.2. For specific guidelines on add-in card design, see Chapter 7, "Add-in Cards and ExpressCard Modules."
As the name suggests, PCI Express is the high-speed, high-bandwidth successor to the ubiquitous Conventional PCI interface found in...
