Gpu will not power up heip

[herbinator]

Hi all
I'm trying to put a mining Rig together in using an Asrock H81 Pro BTC R2.0
I've installed CPU 1 stick Ram and SSD drive all outside of the final case.
So far so good I install windows 10 and boot using the igpu no problems.
Now I plug in my Rx 480 to pci-e slot directly and my graphics card is dead as a doorknob I have 2 other Rx 470 that I've also tried and no power.
I've got everything plugged in firmly the 24 pin and the CPU power connector to mobo..
This board also has 2 extra 4 pin molex power connectors if your going to use more then 3 gpus, I've got them plugged in the PSU is a Corsair platinum A1200i.
I've gone into bios using onboard and messed with the use onboard or pci-e option and the pci-e gen options also tried the cards in the other PCI slots with riser cards I just can not get any power to any of my GPUs, I'm on the latest bios version 1.20, I've also tested the PSU on my existing gaming machine and it powered it up fine.
A week I've been at this please help I'm tearing my hair out!!

 

[herbinator]

Well after pulling my finger out and testing the 3 gpus in my gaming machine.
I had 2 DOA gpus, I can't believe my luck there seems to be quality issues with the latest amd Rx 480/470 both sapphire by the way.
Was convinced it was the motherboard as who'd imagine 2 brand new gpus to be faulty.