PCI Express

What is PCI Express?

PCI stands for Peripheral Component Interconnect. PCI Express has been launched by Intel in 2004 to replace the PCI extension bus. This bus is used as a communication lane to transmit signals and data from your computer system to peripheral devices attached to your computer.

Hence, PCI Express, also known as 3GIO, is a computer expansion card interface, will transmit data along four point-to-point serial data lanes.

How does PCI Express work?

PCI Express, alike Gigabit Ethernet, SATA, and Serial-Attached SCSI, will make use of a high-speed serial link technology to be able to cope with advanced processors and I/O technology.

PCI Express is structured in layers that will be used to run read and write requests that are transmitted by the transaction layer to the I/O devices. This transaction is done through a packet-based and splitting process. The bus bandwidth is different from the normal PCI one as it is not shared but is supplied to each device.

Advantages of PCI Express

1. The bandwidth is particularly high varying with the kind of implementation used, and can reach up to 5-80 gigabits per second.
2. The serial technology used offers a scalable performance
3. There is a point-to-point link for each device to replace the usual shared PCI bus.
4. The small connectors facilitate the implementation for system designers.

PCI Express buses and their bandwidth

1. The PCI Express 1x (250 [500] MB/s) is the most common one used and is present on almost every motherboard.
2. The PCI Express 2x (500 [1000] MB/s) is particularly required for servers.
3. The PCI Express 4x (1000 [2000] MB/s) is also required for servers.
4. The PCI Express 8x (2000 [4000] MB/s)
5. The PCI Express 16x (4000 [8000] MB/s) bears the standard format of all advanced graphic cards
6. The PCI Express 32x (8000 [16000] MB/s) is used by advanced motherboards to supply Crossfire and SLI devices.

You can get further information on the new improvements of PCI on the link: http://www.pcisig.com/home/