PCI-Express 8x Connector Pin Out

The PCI-Express bus supports 1x, 2x, 4x, 8x [20Gbps], 12x, 16x, and 32x bus widths [transmit / receive pairs]. The PCI-Express [PCIe] 8x signal names and pinout are listed in the table below. The 8x wide PCI Express bus is not used on main-stream PC motherboards. Links to additional PCI Express pinout widths are listed after the table. Currently the 1x PCIe bus is being used to replace the PCI bus, and the 16x PCIe interface is replacing the AGP expansion slot. The pinout table listed here is defined in the standard.

PCI-Express 8x PinOut
Pin Side B Connector Side A Connector
# name Description name Description
1 +12v +12 volt power PRSNT#1 Hot plug presence detect
2 +12v +12 volt power +12v +12 volt power
3 RSVD Reserved +12v +12 volt power
4 GND Ground GND Ground
7 GND Ground JTAG4 TDO
8 +3.3v +3.3 volt power JTAG5 TMS
9 JTAG1 +TRST# +3.3v +3.3 volt power
10 3.3Vaux 3.3v volt power +3.3v +3.3 volt power
11 WAKE# Link Reactivation PWRGD Power Good
Mechanical Key
12 RSVD Reserved GND Ground
13 GND Ground REFCLK+ Reference Clock
Differential pair
14 HSOp(0) Transmitter Lane 0,
Differential pair
15 HSOn(0) GND Ground
16 GND Ground HSIp(0) Receiver Lane 0,
Differential pair
17 PRSNT#2 Hotplug detect HSIn(0)
18 GND Ground GND Ground
19 HSOp(1) Transmitter Lane 1,
Differential pair
RSVD Reserved
20 HSOn(1) GND Ground
21 GND Ground HSIp(1) Receiver Lane 1,
Differential pair
22 GND Ground HSIn(1)
23 HSOp(2) Transmitter Lane 2,
Differential pair
GND Ground
24 HSOn(2) GND Ground
25 GND Ground HSIp(2) Receiver Lane 2,
Differential pair
26 GND Ground HSIn(2)
27 HSOp(3) Transmitter Lane 3,
Differential pair
GND Ground
28 HSOn(3) GND Ground
29 GND Ground HSIp(3) Receiver Lane 3,
Differential pair
30 RSVD Reserved HSIn(3)
31 PRSNT#2 Hot plug detect GND Ground
32 GND Ground RSVD Reserved
33 HSOp(4) Transmitter Lane 4,
Differential pair
RSVD Reserved
34 HSOn(4) GND Ground
35 GND Ground HSIp(4) Receiver Lane 4,
Differential pair
36 GND Ground HSIn(4)
37 HSOp(5) Transmitter Lane 5,
Differential pair
GND Ground
38 HSOn(5) GND Ground
39 GND Ground HSIp(5) Receiver Lane 5,
Differential pair
40 GND Ground HSIn(5)
41 HSOp(6) Transmitter Lane 6,
Differential pair
GND Ground
42 HSOn(6) GND Ground
43 GND Ground HSIp(6) Receiver Lane 6,
Differential pair
44 GND Ground HSIn(6)
45 HSOp(7) Transmitter Lane 7,
Differential pair
GND Ground
46 HSOn(7) GND Ground
47 GND Ground HSIp(7) Receiver Lane 7,
Differential pair
48 PRSNT#2 Hot plug detect HSIn(7)
49 GND Ground GND Ground

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 pair, and one receive pair]. PCI Express uses 8B/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 which stands for: Low Voltage Differential Signaling. The Electrical layer of LVDS listed above is described on the LVDS bus page. The function of the JTAG pins listed above are described on the JTAG bus page. The function of the SMbus pins listed above are described on the SMbus page.

PCI-Express 1x Connector Pinout and 1x signal names.
PCI-Express 4x Connector Pinout and 4x signal names.
PCI-Express 16x Connector Pinout and 16x signal names.
Back to the main PCI-Express PCIe bus page.

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Modified 3/05/12
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