ATX (and PCI-E) Power Supply Connector (Socket) Guide

ATX and PCI-E sockets can be a bit of a mine-field, there are various sizes and some thateven look the same from a distance but have subtle differences (PCI-E 6+2 and ATX 8/4+4 I’m looking at you).

Anyway, I have attempted to simplify for you, find the picture of the plug you want to connect to, read about the sockets you can use.  Can’t get easier than that.

Be sure to check the bottom of the page for an extra note about the pin styles and pitches on the PCB side, there are two different variants (at least of the Chinese produced sockets) which take the same plug, but have different pitch at the PCB, fun times huh! 

	ATX 20 Pin Motherboard Socket: ATX 20 Pin Alternative: ATX 24 Pin (4 unused pins)
	ATX 24 Pin Motherboard Socket: ATX 24 Pin
	ATX 20+4 Pin Motherboard Socket: ATX 24 Pin Note:  The “+4Pin” is a different keying to a normal “4 Pin”.  Always use a 24 Pin Socket for a 20+4Pin Connector, a 20 Pin Socket and a 4 Pin Socket won't work.
	ATX 8 Pin (4x 12v, 4x Gnd) Motherboard Extra CPU Power Socket: ATX 8 Pin Note: Take note, this is different to the 8 pin (or 6+2) PCI-E power plug which has 3x 12v and 5x Gnd.  You can easily tell the difference, 4x Yellow wires = this one, 3x Yellow wires = PCI-E.
	ATX 4+4 Pin (4x 12v, 4x Gnd) Motherboard Extra CPU Power Socket: ATX 8 Pin  Alternative: Two ATX 4 Pin sockets, with some space between them.
	ATX 4 Pin (2x 12v, 2x Gnd) Motherboard Extra CPU Power Socket: ATX 4 Pin  Alternative: 6 Pin PCI-E
	PCI Express 6 Pin Power (3x 12v, 3x Gnd) Socket: 6 Pin PCI-E
	PCI Express 6+2 Pin Power (3x 12v, 3x Gnd, 2x Gnd) Socket: 6 Pin PCI-E Note: Obviously using a 6 pin PCI-E socket you can’t connect the +2.  You can NOT use an 8 pin ATX socket to mate a 6+2 as the keying is different.  8 Pin PCI-e sockets are hard to find.  It’s only two extra grounds so I really don’t see the point of them, just leave it hanging.

PCB Pin Pitches/Styles for Chinese Produced ATX/PCI-E Sockets

At least the vertical sockets for the plugs above I have seen come in two different pitches/styles out of China at the PCB side (the “plug side” of the socket is the same for both and fits the plugs on a typical ATX Power Supply).

There is the “5569” Chinese part number style with a solid 1mm square pin and this has a 4.2mm pitch in both X and Y direction.

Then there is the “5566” Chinese part number style with a pointy flat pin and this has a 4.2mm pitch along the rows (so the long direction) but a 5.5mm pitch between the rows (short direction).

See the diagram below, the plug side is the same for both, but you can see the PCB side has a different pitch.