Hi Crytominer,
Well its definitely not a motherboard issue -that's some serious motherboard testing

I was just re-reading your Claymore extract above.
It IS seeing all 6 GPUs in the temperature & fan % readings, just not in the Hashing reading.
So maybe it is a Claymore issue - you should try raising it with him.
In any case with the Pro Duos now available for $800 they are a good Zcash mining option which more people will be using and Claymore should support.
I also suggest you try the official AMD linux drivers for Pro Duo (FirePro which I linked in my first post).
Did you have all 6 GPUs working on Nicehash benchmark using Eth sgminer? (should be doing better than 28 though - would expect 31+ 62 total) See
https://forum.ethereum.org/discussion/6707/radeon-pro-duosIf not you could have a bad GPU?