Today I was switching out a bad hard drive in my farm and noticed something odd, the wires on a 2xmolex -> PCIE8P adapter were sticking together and I couldn't discern a border between them.
Upon closer inspection, it turned out the wires had melted together, I was extremely fortunate that the yellow and black wires were in such a position that they didn't mix and cause a short.
Anyways, I had used the same adapter in other places around the farm, I checked all of them and surely enough, all of them had signs of degradation. Some were melting, some were charring in places, I removed all of them.
So the next step, I cut one of the adapters up to check the wires inside, this is what I found (the yellow one):
https://i.imgur.com/P2l7YZI.jpgThe yellow one is from the molten adapter and is supposed to be 18 AWG (written on the cable as well as the product page in aliexpress where I bought it from).
The black one for comparison is a piece of good quality 20 AWG wire, the black ones core has around twice the diameter!
I don't have a tool to measure gauges that small but by eyeballing it, I'd say the adapter wires are around 24 AWG, not even close to 18.
I got off easy here but a cautionary tale to all: when buying a batch of adapters, get one extra to cut it open and look inside, this could have ended a lot more expensively.