Solvline PCIe - Manual (Page 8)

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About PCI Express
About PCI Express
PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe is a
computer expansion card standard designed to replace the older PCI, PCI-X, and AGP
standards. PCIe 2.1 is the latest standard for expansion cards that is available on mainstream
personal computers.
PCIe, unlike previous PC expansion standards, is structured around point-to-point serial links, a
pair of which (one in each direction) make up lanes; rather than a shared parallel bus. These
lanes are routed by a hub on the main-board acting as a crossbar switch. This dynamic point-to-
point behavior allows more than one pair of devices to communicate with each other at the
same time. In contrast, older PC interfaces had all devices permanently wired to the same bus;
therefore, only one device could send information at a time. This format also allows channel
grouping, where multiple lanes are bonded to a single device pair in order to provide higher
bandwidth.
Unlike preceding PC expansion interface standards, PCIe is a network of point-to-point
connections. This removes the need for arbitration of the bus or waiting for the bus to be free
and allows for full duplex communications. This means that while standard PCI-X (133 MHz 64
bit) and PCIe ×4 have roughly the same data transfer rate, PCIe ×4 will give better performance
if multiple device pairs are communicating simultaneously or if communication within a single
device pair is bidirectional.