:O Points for ingenuity but is that safe?? A 6 pin PCIe plug should be able to handle 75w. Theoretically a molex can handle 11A per pin, so that should be fine, but I'm not so sure about that cheap Chinese PCB. Does it get hot/warm during use?
As far as the connector is concerned (Molex part#45558-0002), it's rated for 8 amps per pin, or almost 300W when all 3 12V pins are connected. You make a good point about the PCB though, which isn't anything near 2oz copper (maybe not even 1oz). It's got a good low-resistance ground pour, but the 12V power trace is relatively small and therefore gets pretty hot. I'm going to shut down the rig and solder on a 18AWG jumper wire for the 12V pins.
p.s. I've updated the blog post and given you credit for pointing out the issue with the PCB trace thickness.