PCI-Express 1x

 

The PCI-Express bus supports 1x [2.5Gbps], 2x, 4x, 8x, 12x, 16x, and 32x bus widths [transmit / receive pairs].
The PCI-Express [PCIe] 1x signal names and pinout are listed in the table below.
The 1x wide PCI Express bus is used as the replacement for the PCI expansion slot on PC motherboards, replacing the older and slower PCI slot.
Pinout tables for the other PCI Express widths are listed below the table.

PCI-Express 1x PinOutPinSide B ConnectorSide A Connector#NameDescriptionNameDescription1+12v+12 volt powerPRSNT#1Hot plug presence detect2+12v+12 volt power+12v+12 volt power3RSVDReserved+12v+12 volt power4GNDGroundGNDGround5SMCLKSMBus clockJTAG2TCK6SMDATSMBus dataJTAG3TDI7GNDGroundJTAG4TDO8+3.3v+3.3 volt powerJTAG5TMS9JTAG1+TRST#+3.3v+3.3 volt power103.3Vaux3.3v volt power+3.3v+3.3 volt power11WAKE#Link ReactivationPWRGDPower GoodMechanical Key12RSVDReservedGNDGround13GNDGroundREFCLK+Reference Clock
Differential pair14HSOp(0)Transmitter Lane 0,
Differential pairREFCLK-15HSOn(0)GNDGround16GNDGroundHSIp(0)Receiver Lane 0,
Differential pair17PRSNT#2Hotplug detectHSIn(0)18GNDGroundGNDGround

PCI Express is the new serial bus addition to the PCI series of specifications. This is a serial bus which uses two low-voltage differential LVDS pairs, at 2.5Gb/s in each direction [one transmit, and one receive pair]. PCI Express uses8B/10B encoding [each 8 bit byte is translated into a 10 bit character in order to equalize the numbers of 1's and 0's sent, and the encoded signal contains an embedded clock]. PCI Express supports 1x [2.5Gbps], 2x, 4x, 8x, 12x, 16x, and 32x bus widths [transmit / receive pairs]. The PCI-Express [PCIe] 1x signal names and pinout are listed above.

The differential pins [Lanes] listed in the pin out table above are LVDS [Low Voltage Differential Signaling]. The Electrical layer of LVDS listed above is described on the LVDS bus page.
The function of the JTAG pins are described on the JTAG bus page. The function of the SMbus pins listed above are described on the SMbus page.