PCI Express

The PCI Express Architecture defines a flexible, scalable, high-speed, serial, point-to-point, hot pluggable/hot swappable interface for expansion cards such as graphics, audio, host adapters, SSD drives and other hardware. The PCI express bus connects to the northbridge making it extremely fast.

motherboard bus

A PCI Express bus consists of one or more data-transmission lanes connected serially. Each lane consists of two pairs of wires, one pair for transmit and one for receive. There are 1, 4, 8 or 16 lanes in a single PCIe slot – written as x1, x4, x8, or x16.

PCI Express Slots

x16 is usually used for high end graphics cards.

Read page 65 of the textbook “Exploring Computer Hardware”.