Hello guys! I am trying to build a 7 gpu mining rig with the following components:

i3 Processor
8gb ram ddr3
MSI z97 gaming 5 Mobo
2x 1000 watts psu
and 7x 480 PowerColor 4g Gpu
USB 3.0 powered risers
on a Win 8.1 Pro operative system.

And I am experiencing issues to have all the cards recognized even after over 8 hours of trying different things like:

Clearing CMOS
Checking risers (they all are working)
Switching back and forward gpus within pcie ports for hours, which allowed me to recognize the 6th card like a regular H81 Pro BTC MOBO.
Everytime I plug a GPU to the PCIE7 slot the system won run. I am about to uninstall everything and start from the OS.

Do you guys have any idea what am I missing?

BTW: I am trying to emulate the process made by Cryptomined (https://www.youtube.com/watch?v=EWVyutw3hZk). But he says something about the memory on the minute 11:55 that  I can not understand with my limited english.

I hope someone can help me! Have a good day miners!

Edit: I just managed to have all the gpu recognized but one of them is still showing error code 43, even after applying the 6gpu mod.