[SOLVED] PCIe x16 6-pin vs 8-pin Question

[1405]

Not sure whether this question should have been asked in graphics cards or not...
I realize that the 6-pin PCIe graphics card connector is good for 75W whereas the 8-pin (6+2) connector is good for 150W. But the only difference I see is that the 8-pin has an couple extra ground (-) wires added for stablity. How does that make any difference in allowing a higher wattage / i.e current carrying capacity? The same 3 x Pos (+) wires still have to draw all that extra current? I haven't noticed any larger guage wires on the 6+2 pin cable than the 6-pin cable per same PSU.

 

[Darkbreeze]

What is the point of the question? What is it that you are trying or wanting to do?

This fully outlines the two types, three actually if you count the 6+2 as being different that the others, which it actually is since it can be both but is still rated for 150 watts regardless.

http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress8

http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress

 

[TJ Hooker]

Strictly speaking the 6 pin connector only has to have two 12 pins, the 3rd is optionally connected.

But yes, the official ratings are a little odd and not necessarily based on the real ampacity of the connectors.

 

[Darkbreeze]

In reality, the existence of the 8 pin connector is more about sense and that graphics card manufacturers wanted to make sure that any PSU attached to the other end of a cable attached to a card that was actually PULLING the kind of load associated with one or two 8 pin cables, was capable of supplying it.

Otherwise, you would see a lot of numbskulls with power supplies that were not really designed to handle that kind of load, but had two six pin connectors, trying to run those kinds of cards off cheaper, lower quality, lower capacity power supplies.

Requiring a PSU to have an 8 pin connector in order to work with a graphics card that requires a load that high was a way to ensure that those kinds of units did not get used with lesser power supplies which is why if you HAVE a card that requires an 8 pin and you do not have a PSU that HAS an 8 pin or a 6+2 pin, you should NOT use that PSU with that graphics card. Obviously, there are companies out there that have created adapters to get around this, but it's not wise to use them because if your unit lacks an 8 pin then it's likely not capable of safely supporting that load.