GIGABYTE GA-X58A-UD3R - How to Enable 5 or 6 GPUs?

[matovicv]

Hello,

Anyone have this board?
https://www.gigabyte.com/Motherboard/GA-X58A-UD3R-rev-10#ov

It has 6 slots (4 x Express x16 + 2 x PCI Express x1), but if i put (5th and 6th card) in 2 of PCI Express x1 i get error in Device manager. Sometimes it's error 43, sometimes it's error 12.

It just will not recognize the 5th and 6th GPU, or just 5th card. Has anyone got 5 or 6 GPU's working with this or a related Gigabyte board?   

Thank You