you're right, according to wikipedia
This is a minor revision from March 2005. The power was slightly increased on all rails. Efficiency requirements changed. Added 6-pin connector for PCIe graphics cards that aids the PCIe slot in the motherboard, delivering 75 watts.
Another minor revision. Added 8-pin connector for PCIe graphics cards that delivers another 150 watts.
I would say 2x6pin b/c it allows more backwards compatibility. ie it's safer to do a 2x molex -> 6pin. usually the 2x6pins are on seperate rails?. the 1x 8pin, if you needed an adapter.. you'd need what 4x molex -> 1x8pin?
That's not true. There are PSUs that have just one 6/8-pin so they can't power a GPU that requires 2x 6-pin without adapter.Answer to OP question is because the set of PSUs with 8 pin connectors is a subset of PSUs that have 6 pin connectors, or other words no PSUs have 8 pin connectors but not 6 pin. Less of a chance customers have problems by using 2 6 pin than having just 1 8pin.
Can't you do that with a single 8-pin connector too? It has multiple 12V pins.Another benefit I can think of is to distribute power load across multiple 12V rails in a PSU.
Did you test this yourself or going by something you read on the net? Wanna share your results or link to the people who claim this?
Well it can be solved by simple logic that it depends on the PSU and not the 6-pin-8-pin connector. If the PSU has the power necessary then the 6-pin can output that figure. All you do to fill a 8-pin female with a 6-pin male is to splice a single wire(correct gauge) with two proper pin ends and plug it into the left over two female pins. It's just ground wires and this is a well known work around.
It has been known since the 8-pin pci-express standard was created. Creating an 8-pin pci-express connector was just a way to idiot proof against the ignorant overloading their power supplies. Possibly to increase sales of new power supplies at the same time.
There isn't really an answer to this question, is there?