Editing PCI Express (section)

=== Derivative forms ===
Numerous other form factors use, or are able to use, PCIe. These include:
* Low-height card
* [[ExpressCard]]: Successor to the [[PC Card]] form factor (with x1 PCIe and USB 2.0; hot-pluggable)
* PCI Express ExpressModule: A hot-pluggable modular form factor defined for servers and workstations
* [[XQD card]]: A PCI Express-based flash card standard by the [[CompactFlash Association]] with x2 PCIe
* [[CFexpress]] card: A PCI Express-based flash card by the CompactFlash Association in three form factors supporting 1 to 4 PCIe lanes
* SD card: The [[SD card#SD Express|SD Express]] bus, introduced in version 7.0 of the SD specification uses a x1 PCIe link
* [[Switched Mezzanine Card|XMC]]: Similar to the [[Common Mezzanine Card|CMC]]/[[PCI Mezzanine Card|PMC]] form factor (VITA 42.3)
* [[Advanced Telecommunications Computing Architecture|AdvancedTCA]]: A complement to [[CompactPCI]] for larger applications; supports serial based backplane topologies
* [[Advanced Mezzanine Card|AMC]]: A complement to the [[Advanced Telecommunications Computing Architecture|AdvancedTCA]] specification; supports processor and I/O modules on ATCA boards (x1, x2, x4 or x8 PCIe).
* [[FeaturePak]]: A tiny expansion card format (43{{nbsp}}mm × 65&nbsp;mm) for embedded and small-form-factor applications, which implements two x1 PCIe links on a high-density connector along with USB, I2C, and up to 100 points of I/O
* [[Universal IO]]: A variant from [[Supermicro|Super Micro Computer]] Inc designed for use in low-profile rack-mounted chassis.<ref name="tNP5L" /> It has the connector bracket reversed so it cannot fit in a normal PCI Express socket, but it is pin-compatible and may be inserted if the bracket is removed.
* [[M.2]] (formerly known as NGFF)
* [[M-PCIe]] brings PCIe 3.0 to mobile devices (such as tablets and smartphones), over the [[M-PHY]] physical layer.<ref name="osiit" /><ref name="PoRghEr" />
* [[U.2]] (formerly known as SFF-8639)
* [[SlimSAS]]

The PCIe slot connector can also carry protocols other than PCIe. Some [[List of Intel chipsets|9xx series Intel chipsets]] support [[Serial Digital Video Out]], a proprietary technology that uses a slot to transmit video signals from the host CPU's [[Intel GMA|integrated graphics]] instead of PCIe, using a supported add-in.

The PCIe transaction-layer protocol can also be used over some other interconnects, which are not electrically PCIe:
* [[Thunderbolt (interface)|Thunderbolt]]: A royalty-free <!-- as of Thunderbolt 3 --> interconnect standard by Intel that combines [[DisplayPort]] and PCIe protocols in a form factor compatible with [[Mini DisplayPort]]. Thunderbolt 3.0 also combines USB 3.1 and uses the [[USB-C]] form factor as opposed to Mini DisplayPort.
* [[USB4]]