We have dell r515 and we want to use 2x samsung pci-e nvme. We installed them on the server but the server detected only 1 nvme. We checked each slot separately by setting only 1 nvme and it was ok, the server detected nvme in each slot. But if we put 2 nvme-cards at the same time - the server detected only one card. Also we tried use other nvme-cards - the result was the same. 

All firmware (bios included) has been updated to the latest version.

It this problem with hardware or firmware?