A 6-pin can handle more then 75 watts of power. For example if a 6 pin were restricted to 75 watts then we would be getting 2.08A per 12v yellow cable 2.08*3*12 = 75 watts , but awg 18 are able to deliver up to 10A per yellow under optimal circumstances , so theoretically 10*3*12= 360 watts. But thats the cable then we have the terminals..
Standard terminals are rated for 8amps then there is HCS terminals that are rated for 11amps and Plus HCS terminals 12amps
so with a 6-pin pcie with 2*8*12= 192 watts from 6 pin pcie 18awg
8-pin pcie with 3*8*12= 288 watts 8 pin pcie 18 awg
So 6 pin 75 watts of power rating are vastly underrated.
Thanks for the detailed info.
I currently use, just to play it safe, a coupler cable which goes from two 6 pins into a single 8 pin, so on a single HP 1200w server power supply and a 12x6 breakout board, I can run a maximum of 3 1080 Ti's (which require two 8 pin's each), as this would then require four 6 pins per 1080 Ti. Is this overkill? Or could I safely do away with the dual 6 pin coupler to single 8 pin, and just use a single 6 pin to 6+2 cable into each 1080 Ti 8 pin port?