I'm not using this specific board, but I am using a board that provides extra molex connector which supplements the PCI-E lanes. I am running 5x GPU R9 280x per board. I use all powered risers and the extra molex on the board. Did your comment apply only to the specific board that was on topic or all with PCI-E supplement molex? I've been successfully running 2x rigs this same way for almost 3 months now with no issues...
As I did, a year or so ago, with a gigabyte G1.sniper3. It still mines to this day with 4 7970's.
I give up, not like anyone reads what you say anyway.