I believe you've seen the molex to barrel adapter that takes 5 minutes to make. It's a lot safer power if you have the PSU for it. Yellow 12V line to the inside shielded wire, and the two center grounds on the molex to the outside braided ground.
The two Jally PSUs I've butchered have had a red and black wire inside, no shielding. Red is centre positive. I just solder on to an old molex fan cable (I've heaps of them from years ago), bit of heat-shrink, job jobbed.