Pcie Connector Pin Assignment

PCI Express Card

PinSymbolTypeLegend
1gnd
2usb d-I/OUSB Data
3usb d+I/OUSB Data
4cp usb#OCard use USB bus
5rsvd0Reserved
6rsvd1Reserved
7smb clkSM Bus Clock
8smb dataSM Bus Data
91.5 volt
101.5 volt
11wake#OWake up main CPU from card
123.3 Volt auxProvided when main CPU is off (support for WAKE)
13pe rst#IPower Good (reset)
143.3 Volt
153.3 volt
16clk req#OClock Request - enable ICS9DB106
17cp pe#OCard us PCI Express bus
18refclk-IClock input from buffer ICS9DB106
19refclk+IClock input from buffer ICS9DB106
20gnd
21PERn0IPCI Express RX -
22PERp0IPCI Express RX +
23gnd
24PETn0OPCI Express TX -
25PETp0OPCI Express TX +
26gnd
  • Verified with Congatec design

PCI Express - 1-lane slot

PinSymbolTypeLegend
a01PRSNT#1Hot-Plug presence detect
a02+12V
a03+12V
a04gnd
a05jtag2JTAG - Clock
a06jtag3JTAG - Data In
a07jtag4JTAG - Data Out
a08jtag5JTAG - Mode Select
a093.3 Volt
a103.3 Volt
a11PERST#IPower Good (Reset)
a12gnd
a13refclk+IClock input from buffer ICS9DB106
a14refclk-IClock input from buffer ICS9DB106
a15gnd
a16PERp0IPCI Express RX +
a17PERn0IPCI Express RX -
a18gnd
b01+12V
b02+12V
b03rsvd0Reserved
b04gnd
b05smb clkSM Bus Clock
b06smb dataSM Bus Data
b07gnd
b083.3 Volt
b09jtag1JTAG - Reset
b103.3 Volt auxProvided when main CPU is off (support for WAKE)
b11wake#OWake up main CPU from card
b12rsvd1Reserved
b13gnd
b14PETp0OPCI Express TX +
b15PETn0OPCI Express TX -
b16gnd
b17PRSNT#2Hot-Plug presence detect
b18gnd
  • Verified with PCI Express official specification

PCI Express Mini Card

RowPinSymbolTypeLegendStatus
01WAKE#
03COEX1Function is OEM specificchanged
05COEX2Function is OEM specificchanged
07CLKREQ#ORequest to ICS9DB106 for clock signal, MiniCard can tie to ground. USB-only cards leave this open.
09Gnd
011REFCLK-IClock input from buffer ICS9DB106
013REFCLK+IClock input from buffer ICS9DB106
015Gnd
017ReservedReserved for future SIM Card pin C8
019ReservedReserved for future SIM Card pin C4
021Gnd
023PERn0IPCI Express RX -
025PERp0IPCI Express RX +
027Gnd
029Gnd
031PETn0OPCI Express TX -
033PETp0OPCI Express TX +
035Gnd
037Gndchanged
0393.3Vauxchanged
0413.3Vauxchanged
043Gndchanged
045Reserved
047Reserved
049Reserved
051Reserved
123.3 Vauxchanged
14Gnd
161.5 Volt
18UIM PWROSIM Card
110UIM_DATAI/OSIM Card
112UIM_CLKOSIM Card
114UIM_RESETOSIM Card
116UIM_VPPOSIM Card
118Gnd
120W_DISABLE#IWireless disable (active low)changed
122PERST#IPower Good (Reset)
1243.3Vaux
126Gnd
1281.5Volt
130SMB CLKISM Bus Clock
132SMB DataI/OSM Bus Data
134Gnd
136USB_D-I/OUSB Data
138USB_D+I/OUSB Data
140Gnd
142LED_WWAN#OActive low, max 9mA
144LED_WLAN#OActive low, max 9mA
146LED_WPAN#OActive low, max 9mA
1481.5Volt
150Gnd
1523.3Vauxchanged
  • Verified with PCI Express™ Mini Card Electromechanical Specification, 1.0, with ECN

PCI Express Cards - Compare Electrical Interfaces

SignalExpressCardExpress SlotExpress MiniTypeLegend
PERn0YesYesYesIPCI Express RX -
PERp0YesYesYesIPCI Express RX +
PERST#YesYesYesIReset (Power Good)
PETn0YesYesYesOPCI Express TX -
PETp0YesYesYesOPCI Express TX +
refclk-YesYesYesIClock input from buffer ICS9DB106
refclk+YesYesYesIClock input from buffer ICS9DB106
smb clkYesYesYesISM Bus Clock
smb dataYesYesYesI/OSM Bus Data
wake#YesYesYesOWake up main CPU from card
CLKREQ#YesYesOClock Request - enable ICS9DB106
usb d-YesYesI/OUSB Data
usb d+YesYesI/OUSB Data
cp pe#YesOCard us PCI Express bus
cp usb#YesOCard use USB bus
COEX1YesFunction is OEM specific
COEX2YesFunction is OEM specific
LED_WLAN#YesOActive low, max 9mA
LED_WPAN#YesOActive low, max 9mA
LED_WWAN#YesOActive low, max 9mA
UIM PWRYesOSIM Card
UIM_CLKYesOSIM Card
UIM_DATAYesI/OSIM Card
UIM_RESETYesOSIM Card
UIM_VPPYesOSIM Card
W_DISABLE#YesIWireless disable (active low)
PRSNT#1YesIHot-Plug presence detect
PRSNT#2YesOHot-Plug presence detect
jtag1YesIJTAG - Reset
jtag2YesIJTAG - Clock
jtag3YesIJTAG - Data In
jtag4YesOJTAG - Data Out
jtag5YesIJTAG - Mode Select
+12VYespwrPower 12 Volt
1.5 VoltYesYespwrPower 1.5 Volt
3.3 VoltYesYespwrPower 3.3 Volt
3.3 Volt auxYesYesYespwrPower 3.3 Volt, also present if main CPU is off, support for WAKE#
GNDYesYesYespwrGround

References

Category:Buses Connectors

Hacking GPU PCIe power connections


Until recently, I never thought much about PCIe power connectors.  Three 12 power and three ground wires was all I thought there was to them.  I thought it was odd that the 8-pin connectors just added two more ground pins and not another power pin, but never bothered to look into it.  That all changed when I got a new GPU card with a single 8-pin connector.

My old card had two 6-pin connectors, which I had plugged a 1-2 18AWG splitter cable into.  That was connected to a 16AWG PCIe power cable, which is good for about 200W at a drop of under 0.1V.  My new card with the single 8-pin connector wouldn't power up with just a 6-pin plug installed.  Using my multi-meter to test for continuity between the pins, I realized that it's not just a row of 12V pins and a row of ground pins.  There was continuity between the three 12V pins, and between three of what I thought were five ground pins.  After searching for the PCIe power connector pinout, I found out why.
Diagram edited from http://www.overclock.net/a/gpu-and-cpu-power-connections

Apparently some 6-pin PCIe cables only have 2 12V wires, 2 ground, and a grounded sense wire (blue in the diagram above).  With just two 12V wires, a crap 18" 20AWG PCIe power cable would have a drop of over 0.1V at 75W.  Since the 8-pin connector has three 12V pins, it can provide 50% more power.  My 6-pin 16AWG PCIe cable would have voltage drop of only 40mV at 75W, so I just needed to figure out a way to trick the GPU card into thinking I had an 8-pin connector plugged in.  The way to do that is ground the 2nd sense pin (green in diagram above).

I didn't want the modification to be permanent, so soldering a wire to the sense pin was out.  The PCIe power connectors use the same kind of pins as ATX power connectors, and I had an old ATX power connector I had cut from a dead PSU.  To get one of the female contacts out of the ATX connector, I used a hack saw to cut apart the ATX connector.  Not pretty, but I'm no maker, I'm a hacker. :-)  I stripped the end of the wire (red in the first photo), wrapping the bare part of the wire around the screw that holds the card bracket in the case.  I powered up the computer, and the video card worked perfectly.

Looking for a cleaner solution, I decided to make a jumper wire to go between the sense pin and the adjacent ground.  I also did some searching on better ways to remove the female contacts from the connectors.  For this, overclock.net has a good technique using staples.  When the staples aren't enough to get the contacts out, I found a finish nail counter-sink punch helps.

Here's the end result, using a marrette (wire nut) to make the jumper:

0 thoughts on “Pcie Connector Pin Assignment

Leave a Reply

Your email address will not be published. Required fields are marked *