Question Advice on how to configure BIOS for a dual GPU & NVME RAID 0 setup?

[Zii]

Link to motherboard specs. It's an x370 board with a Ryzen 1700x installed.

After quite a bit of tweaking and frustration, I was able to get two 660p (M.2 NVME) drives running in RAID 0. Works flawlessly and I'm very happy with the results.

However, I had a crossfire Vega 64 setup. First card in PCIE_X16/X8_1, 2nd card in PCIE_X8_2. Bottom PCIEX4_3 is empty because GPU will not fit in the case.
Highlighted are the only slots I have populated:

Motherboard manual states the following:

Since I have both M.2 slots populated, and both PCIE slots populated with Vega 64 GPU's, how do I configure my BIOS to get the 2nd GPU running? It does not show up in BIOS, and does not show up in windows under device manager.
I don't care if both GPU's need to be run at x8/x8, or x8/x4, or even x4/x4, I just need them to work alongside the RAID ) m.2 drives.

How would i go about this? I find it difficult to believe an expensive SLI/crossfire mobo won't work with crossfire/SLI if both m.2 slots are being used. Otherwise, what's the point?

I am not using an SATA ports whatsoever, just the m.2 as storage. If I could "steal" bandwidth from them, that'd be perfectly fine.

I'm just really confused because bios has x8/x4/x1 and gen1/gen2/gen3... I have no idea what that means I don't want to risk damaging anything by randomly changing the settings. Help?

 

[Zii]

So... is it really impossible to have two graphics cards in a motherboard specifically designed to support triple crossfire, while also using both provided M.2 slots?
That sounds a little bit insane to me. I don't understand why I can't find any information regarding this issue anywhere on the internet.