I have the same MB, CPU but mining with 6x470s

From the GPU-Z screen, I'd say something is wrong with the OC - some of the cards are running with default voltage. Also wondering how your GPU3 is using significantly less watts (almost impossible).....
I have been testing all ports on the MB. PCI-E ports 2 and 3 are broken. When I using different carts on these ports using less watts and not stable. When I use GPU cards on PCI-E ports 1, 4, 5 and 6 i have stable hashing rate and using 100 watt. You can see here