The previous standard, PCI Express 1.1, has a speed limit of 2.5GT/s, or giga transfers per second. PCI Express 2.0 doubles this to 5GT/s. Bandwidth per lane has also increased from 500Mb/s to 1Gb/s, and according to their release, “It effectively increases the aggregate bandwidth of a 16-lane link to approximately 16 GB/s. The higher bandwidth will allow product designers to implement narrower interconnect links to achieve high performance while reducing cost”.

The first products designed to work with PCI Express 2.0 are yet to appear, but must surely be due soon now that the new standard has been released.

According to the PCI SIG, other benefits of the new standard are numerous. They include:

Dynamic link speed management – to control the speed at which the link is operating

Link bandwidth notification – to notify software (operating system, device drivers, etc) of changes in link speed and width

Capability structure expansion – to expand the control registers to better manage devices, slots and the interconnect

Access control services – optional controls to manage peer-peer transactions

Completion timeout control – to define a required disable mechanism plus related optional enhancements

Function-level reset – optional mechanism to reset functions within a device

Power limit redefinition – to redefine slot power limit values to accommodate devices that consume higher power

The PCI SIG also advise that the 2.0 spec has been updated with numerous errata and editorial changes for enhanced consistency and readability.

Given that processing technology is moving so quickly, with Intel and AMD already showcasing 8 core processors, and HP announcing a way to defeat Moore’s Law by packing ever more transistors onto a processor, it makes me wonder how soon before a PCI Express 3.0 standard will be necessary. No doubt it’s already on the drawing board.

But until then, if you’re building or buying a new computer, and care about the components that are installed within, you’ll be looking for a motherboard that supports PCI Express 2.0 and cards to go with it!
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Alex Zaharov-Reutt  Hardware