Motherboard shouldn't matter - I have run Polaris GPUs on even OLDER boards in the past.
Does GPU-Z detect that GPU? It isn't unlikely at all that you have a BAD RISER, not an issue with the MB.
I tried with riser and direct pluging in mitherboard. Both way didn't work. Yes gpu-z detect it but when i check opencl in gpu-z it says device not found.