WRX80-SU8-IPMI and Quad NVMe cards

Hello,

I have this board with the latest F6 BIOS, and have been trying to get a quad NVMe card (with four NVMe SSDs) to work with any slot. I know that you can set slots to Auto or force bifurcation to x4 x4 x4 x4, and I've tried that already, with no success. All that happens is one drive shows up. I've also tried other brands of cards, with no success either. Now, I have to use one SSD in each of four slots, which works fine but I need those three extra slots.

Any thoughts and experience on this is a massive help. Cheers!