Same. Molex converters are bad. You are asking for melted wires. Literally.
The rule is 1 proper Pci-e power connector and one molex converter per card, never had any problems doing it that way.
You will one day. The PCI-E connector has 6/8 wires for a reason. You'll get away with it on graphics cards but ASIC hardware often goes well beyond the 75w/150w PC standard.
Ofc, but now I said "per card" hinting at graphics card usage where anything but a 7990 should be fine with a 6/8 pin + molex coverter. Besides 1x6 pin connector can handle 150w+ easily, just look at the overclocked antminers.