PCI Express.

PCI Express is based on a type of serial communications technology somewhat like that in USB or SATA hard drives. The mechanical (physical) board connectors come in one of four types: x1, x2, x4, and x16 (see illustration below) in order to meet different peak bandwidth requirements.

PCI Express Technical Specs:

* Full duplex point-to-point topology
* Differential low voltage interconnect
* Embedded clocking
* Scalable frequency: Initial Bit Rate: 2.5Gb sec/lane/direction
* Scalable bandwidth - data layer is scalable to 1x, 2x, 4x, 8x, 12x, 16x, 32x lane widths
* Each PCI Express "lane" uses 4 wires - one differential pair for transmit and one pair for receive

* Note: PCI Express is NOT the same as PCI-X slots, it is a totally new technology.


PCI Express Bandwidth
LANES
Peak Bandwidth (Duplex Mode)
x1
500MB/s
x4
2 GB/s
x8
4 GB/s
x16
8 GB/s
PCI express is a highly flexible, reliable, modular and scalable design that will eventually replace all PCI slots on the motherboard and AGP slots. It has better power management, native hot-plug support, backwards compatibility with PCI software, support for streaming media (such as video camera or TV), and truly scalable configurations. In addition:
Compatible with existing PCI drivers and software and operating systems
High bandwidth per pin. Low overhead. Low latency
Ability to scale speeds by forming multiple lanes
A point-to-point connection, allows each device to have a dedicated connection without sharing bandwidth
Ability to comprehend different data structures
Low power consumption and power management features
Hot swap-ability and hot plug-ability for devices
Supported by nearly 500 system hardware vendor
PCI Express and 3D Graphics
The x1 PCI Express slots will easily replace the standard 32-bit PCI slots and have four times the bandwidth.