Editing PCI Express (section)

=== PCI Express External Cabling <span class="anchor" id="EXTERNAL-CABLING"></span> ===
''PCI Express External Cabling'' (also known as ''External PCI Express'', ''Cabled PCI Express'', or ''ePCIe'') specifications were released by the [[PCI-SIG]] in February 2007.<ref name="pcie_cabling1.0" /><ref name="ZTXPi" />

Standard cables and connectors have been defined for x1, x4, x8, and x16 link widths, with a transfer rate of 250&nbsp;MB/s per lane. The PCI-SIG also expects the norm to evolve to reach 500&nbsp;MB/s, as in PCI Express 2.0. An example of the uses of Cabled PCI Express is a metal enclosure, containing a number of PCIe slots and PCIe-to-ePCIe adapter circuitry. This device would not be possible had it not been for the ePCIe specification.

==== PCI Express OCuLink <span class="anchor" id="OCULINK"></span> ====
''OCuLink'' (standing for "optical-copper link", as ''Cu'' is the [[Symbol (chemistry)|chemical symbol]] for [[copper]]) is an extension for the "cable version of PCI Express". Version 1.0 of OCuLink, released in Oct 2015, supports up to 4 PCIe 3.0 lanes (3.9&nbsp;GB/s) over copper cabling; a [[fiber optic]] version may appear in the future.

The most recent version of OCuLink, OCuLink-2, supports up to 16&nbsp;GB/s (PCIe 4.0 x8)<ref name="OCuLink2" /> while the maximum bandwidth of a [[USB 4]] cable is 10GB/s.

While initially intended for use in PCIe interconnections in servers, OCuLink's popularity lies primarily in its use for laptops for the connection of powerful external GPU boxes, a more prevalent application.<ref name="6MiK5" />