Okay. So the 4th card on the riser but "use" the molex>sata adapter, and sata chain to PSU?
Double checking in case it melts again.
Strongly advise don't do this. Sata connectors are designed to safe for up to 4.5 amps. The risers could draw up to 6 amps especially using 1080ti. Much better to use 2 molex on one string. Each molex won't have a problem as each can do 11 amps. The only issue is the wire will get a little warm but not enough to be dangerous.
On paper you'r right, but from experience the specs are not very accurate.
I'm confident in saying that Molex can't handle 132 watts without getting very hot or even melting due to poor connectivity and +30°C at 11A is not exactly intenteded for 0-24 use. In a 30°C rig that's already 60°C which is just on the borderline of being too painful to touch for more than a few seconds.
In addiction, in my experience Sata is getting sold short; it can handle way more than 54 watts without even getting slightly warm.
Personally, I would much rather use each Sata port with a Sata to Molex cable at 60W then putting 2 cards on one Molex cable.
I agree in as much as I wouldn't feel comfortable pulling 11 amps through a molex even though it is rated for such. But the max a riser will take is 6.24 amps and at that level, the molex shouldn't get warm at all. No matter how many connectors being used on a string, the amount of current each connector handles doesn't change. The main issue with multiple connectors on a string is the wire is carrying more current resulting in increased heating and temperature drop.
I would never put more than the rated current though a sata connector. Yeah usually they are over engineered to handle a bit more but then you're relying on the quality of manufacture to exceed the spec sufficiently. Also, the surface area of the 3 12 volt contacts in the sata is so small compared to the molex pin, if one contact fails or gets dirty or something then it will heat up rapidly as it tries to suck the current though the 2 remaining.
A lot of people use sata connectors to power risers and it's rarely a problem - until it is. I just don't want to take any chances and prefer to just buy a big enough high quality power supply so I don't need to even consider it.