How do IIO/IOU PCIE ports work in AMIBCP?

I am trying to make PCIE bifurcation to my Asus Z10PE-W8 dual socket MB and I know that IIO/IOU ports are not directly linked to physical numbering scheme.
Can I make any deduction from original settings? Could I assume some IIO groups is related to spesific physical socket? Why there is some settings auto and the some other is preset to static value?