https://www.facebook.com/mlacom.si2-3 rigs/day, only using asrock h61/h81 btc boards and ONLY 6x powered risers per rig. both molex connected on every mobo. seeing posts with too much power etc..go back to school
the reason with melted risers and broken boards:
-bad risers
-general noob mistakes, seen all and some are briliant fail.
-cross conected riser/main power from two different psus. use the same psu for riser and main gpu power on every card. dont power the riser from one psu and main gpu power from other psu. usually 3+3 cards or 4+2 cards
-main reason that all web is searching for an answer: SOME PSUS DONT ALLOW BRIDGE MODE. its a psu design, mostly cheaper psus has huge ripple when no mobo connected. just melted risers if you are lucky, more damage if you are not. wont list known psus here.