You're slightly wrong, cyper didn't burn up his cx600m. He was using an extender cable on his cpu power cable and the extender burned up. I'm currently using the same cx600m that has a single pcie with split ends. At default clocks, the psu is holding up well. The wire gets extremely warm but not hot. I don't understand how people read one thing and get it all switched around and post something different. It's like that gossip game kids play where you whisper something in someone's ear and pass it down. So much wrong info by the end of it.
I'm running an overclocked antminer powered by a single strand with two PCI-E ends. Yep, wires are very warm, but not hot.
I couldn't get a single definitive answer as to what ampacity are the AWG18 wires capable of, figures are ranging from 10 to 16 Amps. The lower estimate is enough for a stock clock miner (10 Amps * 3 wires * 12V = 360 Watts). And an overclocked one should draw less than 12 Amps per wire, so also sorta kinda good. But I'm still thinking, it would be a good idea to buy a two-molex-to-PCI-e adapter, cut it and feed a couple more wires (+12V and Gnd) into the power terminals of each blade.