Mini-Fit does not melt at 100W unless significantly damaged. Molex's own spec for eight circuits onto a PCB is 10A per circuit at 16AWG (120W) for 30C temperature rise over ambient. You could run 360W on 3+3 pins before you even brush up against the safety margins which, again, are given with a third more heat since they assume all eight circuits are carrying load. Conversely, I've seen cards with two 8p connections burn one up at under 200W loading, because the receptacle was bent and didn't make proper contact.