Here are some pics of how we made the harness. My buddy owns a cable manufacturing company and even using $120,000 of equipment, the time and effort was not worth it. I only made these because of the delivery time to get J4bberwock boards for the first 52 Antminer S5's.
I highly recommend not even consider doing harnesses and just buy the boards.
The equipment we used to do this project was an auto feed wire cutting and stripping machine that did all the 10 gauge black and reds. Then we used an automatic stripping machine to get .6" on the pre-made PCIE wires we got from klondike_bar. An ultrasonic welder was use to join the wires. Had to use a 150 watt soldering iron to join the welded pads to the power supply.
There is also a shot of the power meter when the room was hot and the fans were at max, it was drawing 3785 watts.
http://i.imgur.com/CFaH9p7l.jpghttp://i.imgur.com/dF4tHgdl.jpghttp://i.imgur.com/hYmu76ol.jpghttp://i.imgur.com/p5snliql.jpgI put in bold letters the advice from the only guy that did it to my knowledge.
