I used this BIOS to get it to work, but I have 2 PCIe boards with 2 x 4 NVME’s and only see 5 NVME’s not all 8. Not sure if you want to see only 4 and have the Asus X99 Deluxe II, then this will work.
EDIT, I have it working with GFX card and another NVME in another slot, I can see 6 NVME’s one being my boot drive see my post here.