Same config as you, 13 cards. Using MBO's PS for 4 GPU's and HP server PS for the rest of them.
Like this one ?
http://www.priceminister.com/offer/buy/138559720/hp-common-slot-platinum-power-supply-kit.html?bbaid=2874447373&sort=0&xtatc=PUB-%5Bggp%5D-%5BInformatique%5D-%5Bcomposants%5D-%5B138559720%5D-%5Boccasion%5D-%5Bhappyvpc+-+Occasion%5D&ptnrid=pt%7C79136307203%7Cc%7C53440930763%7C138559720&t=180112&ptnrid=sIBdSYTew_dc|pcrid|53440930763|pkw||pmt|&gclid=CjwKCAiAm7LSBRBBEiwAvL1-L-YolASd7Ye2EEdWoEt0PuSejw2aPXQJKSGf1NHwQWmd8FpBNlT2zxoCSuIQAvD_BwE
Can you take and post a photo of your bridging pins for type of PSU ? plz