Issue with 6 GPU, risers, mobo and booting

Hey guys, just a follow up post to: my first post. Okay so, this is what my rig looks like. As you can see only 1 card seems to work regardless of what slot I put it in, I don't know if it's the risers but they are USB powered risers, I've tried everything from enabling exceed 4G in BIOS, to Gen1 on all PCIe slots etc but nothing works.

I've installed the latest driver just to get things going and still nothing. For formatting purposes I'll list my issues so it's easier to read:

1. PC won't boot to Windows after I uninstalled driver and restarted PC to install a previous driver reset BIOS fixed this
   
2. 1 GPU detected, other 5 no where to be found
   
3. Tried all BIOS tricks, updated BIOS, 4G+, Gen1 PCIe etc all enabled
   

and main specs are:

1. MOBO: ASUS H270-PLUS
   
2. RAM: 8GB 2400mhz Corsair
   
3. GPU: 6x RX470 XFX
   
4. PSU: Corsair AX1200i
   

I'm completely stuck with this.