I have a Samsung 970 EVOPlus Nvme in the top position under the graphics card and all is well with that setup.
I then thought I would add a second Nvme (pcie) in the bottom position, well nope, windows will not boot. Tried another Nvme in that slot still no full boot. Tried a PCIE card adaptor carrying the Nvme in the bottom PCIE slot, just the same no go. Windows starts to boot and then stops and says it's hit a problem and reboots. Any ideas??