8 Pin or 6+2 Pin PCI-E Power Connectors.

stchman · Mar 13, 2015

OK, when using say a 750W power supply with a single 12V rail using a 8 pin to 2x(6+2) splitter is OK. No need to connect up another 8 pin PCI-E cable.

My reasoning is that since the power supply in question is a single rail 12V, it does not matter.

Also, the spec for PCI-E 6 pin is 75W and 8 pi is 150W. Since the connector is coming from an 8 pin port on the power supply, the 6 pin should be able to indeed supply 150W as well, the only difference is the 2 additional ground wires.

Eximo · Mar 13, 2015

Sort of...

With a single rail all of the power comes from a single place, but it still has to use the wires to get where it needs to go. Depending on the gauge of the wire in the cables you may actually need the 3 12V wires to carry the required amount of power. Undersized wires will have a voltage drop increase as temperature increases.

Regardless most video cards won't fire up unless all of their required pins are populated.

WyomingKnott · Mar 13, 2015

Eximo is right but not emphatic enough. It's not "Sort of." It's "No."

The wires can a) Not supply the full 150W due to resistance, and b) melt. There's a reason for standards, and it's safest to follow them.

stchman · Mar 13, 2015

WyomingKnott :

Agreed, but the 6+2 pin originate from an 8 pin going back to the power supply, so in essence the 6 pin should be 150W as both 6 pin and 8 pin have only 3 12V wires.

Eximo · Mar 13, 2015

A 6 pin connector has 2 grounds, 2 12V+ and one sensor wire. The sixth is unpopulated or used as an extra ground. An 8-pin has an additional ground and an additional 12V+.

That was the purpose of the sort of there is no real necessity to use two or three wires. You could use a single wire from a single rail. It just has to be big enough. The point of using sets of wires all carrying the same voltage is to spread the load between them.

It isn't likely you will cause a meltdown only running two wires. 75W is being very conservative with 18 gauge wire across such short distances. Closer to 60W per wire, so 120W and 180W without a significant voltage drop. There are many power supplies that run a 6-pin from the supply to a 6+2 or even a set of 6+2 connectors. All comes down to the wire size and the ratings. I know EVGA uses 16 gauge wire in some of its supplies to achieve this.

stchman · Mar 13, 2015

Eximo :

The original 6 pin PCI-E, yes the 3rd 12V wire is not connected.

The 6+2 pin PCI-E power connectors that 3rd 12V wire is indeed connected as the you can put the additional 2 grounds in an 8 pin PCI-E equipped video card.

Eximo · Mar 16, 2015

Yes, or as an additional ground, had that in there...

Hopefully you've learned a little bit about low-voltage wiring along the way.

Search

8 Pin or 6+2 Pin PCI-E Power Connectors.

stchman

Distinguished

WyomingKnott

Eximo

Titan

WyomingKnott

Legenda in Aeternum

stchman

Distinguished

Eximo

Titan

stchman

Distinguished

Eximo

Titan

TRENDING THREADS

Latest posts

Moderators online

Share this page