Running 300W on 75W designed connector seems like terrible idea.
But those connectors are very popular, people are buying them and giving top marks.

I have 1300 EVGA Supernova running just 6 cards using 780W.
I'm thinking about expanding the rig, but PSU has connectors for "just" 6 GPUS.

How to connect safely 2 more GPUs?
I want to be 100% sure it's safe, safety is top priority after all, don't want to burn house trying to earn couple of bucks.