I'm confused and wondering if anyone had a similar setup, or can read better than me. Tried googling but getting conflicting information.

Currently: Rampage V (USB 3.0), SLI GTX 970 (16X, 8X) and a 5820K (28 Lanes).

I was toying with getting a SM961 M.2 NVME but have also got the Galaxy S8, so was also looking at getting at USB 3.1 Card (which would seem to need to take up 4X lanes). I'd obviously like this working at X4 rather than x2 (or not at all)

I'm happy with the SLI's going into 8X/8X as my understanding is that won't make much of a performance difference.

I'm trying to reread the manual to check the lanes - pages 1-18 1-19 (http://dlcdnet.asus.com/pub/ASUS/mb/LGA2011/Rampage_V_Extreme/E9550_rampage_v_extreme_ug_WEB.pdf)

What I understand.
It has 6 Pcie slots (4 x PCie 3, and 2x PCie 2)

Because of the 5820K "The PCIE X8_4 will be disabled" but it also shares bandwidth with the M.2.
Now, with 28 lanes, SLI in 16X/8X (and their example of using 3 way SLI in 8X/8X/8X) that should leave x4 for the M.2 and I want to assume that's what will happen, but I've learnt not to assume.
Is it disabling that PCIe slot to ensure the M.2 has the bandwidth, or is it also disabling some (X2) or all of the M.2 lanes?
More simply, Will it work at 4X?

On the USB card, and I appreciate I may be pushing this even further, it seems to be able to use a PCIe 2 slot, and there should be one free. Or I could use the other PCIe3, happy either way.
But if the M.2 was in there (and worked) I'd already be using the 28 lanes.
Would adding the card force the X16 GPU into X8 (or if I did that manually) and be ok?

I can see jumpers for the lanes but these seem to turn them completely on, or off, not change the speed. Page 3-35 seems to suggest I can force the speeds though.

Thanks in advance, appreciate I've got myself muddled here so any help is appreciated. Sorry for length.

(Happy to take advice on the M.2 as well if anyone has an opinion)