I'd recommend buying a heavy duty, quality power supply, like my Seasonic 1100W
It is totally worth the bigger up front costs for three reasons off the of my head:
1) you wouldn't have this problem, and you'd have room to expand
2) the much greater power efficiency translates into $$$$ savers for miners that are going 24/7
3) feasibly the thing could last you the next decade or more. While every other compnent in your PC will be hopelessly outdated, in the year 2024 (wow is that only 10 years away, that's crazzy) your new 512gigahertz core i19 will likely still be compatible with your ancient powersupply, and because it is seasonic I think it will still work as well.
4) The mess of molex to PCI-e power plug adapters doesn't burn your home to the ground.
It's a multi rail supply, with a lot of rails. This is most certainly your problem.
Please, know what you are doing before you do it. Daisy chaining adapters like that will overheat individual wires, and that is what causes fires.