Was this a factory made (soldered) Molex connector or "home made"? I'm asking this because the naked end of the two 12V (yellow) wires seem to have been twisted together, it seems unusual to be, but I may be wrong or in may be the result / visual artefacts of melting. From personal experience, bare wires inserted straight into a PCI-e 6/8 pin or Molex connector almost ends up badly after a few days when not just hours. Generally it starts overheating, any traction on wires may cause short circuits - at best just sparks and PSU shutdown, possibly nastier. Meltdown with soot on wires with also occur after overheating becomes excessive.

It would be interesting to see how you had wired the other end too, on the Blade side.