While the PCI Express Base Specification does not include specific cable requirements for a PCI Express interconnect, it doesn't preclude their use either. In fact, the flexibility of the PCI Express interface actually opens up several options for different implementations of the interconnect. For example, you might use a cable to transmit PCI Express signals from one component to another. The ability to transmit PCI Express signals over a cable can allow for innovative chassis design and usage models.

Currently, the PCI-SIG has not released a formally approved specification about cabling architecture or requirements. In other words, there is currently no such thing as a "PCI Express cable." If you choose or need to use a cable to support your PCI Express implementation, you are on your own in terms of the type of cable and cable headers or connectors that you may use. The absence of a formal standard can make it difficult for your designs to incorporate an external cable interface that can connect to another vendor's PCI Express components.

Using a cable-based interconnect within your system's chassis, however, can have some advantages for your design for example, when you have to connect together PCI Express components located on separate PCBs within your own system or chassis. If you choose to use a cablebased interconnect, make sure that the selected cable can meet all of the electrical signal quality requirements of the interconnect, such as having low loss and jitter. The same requirement...