Hi Crispychris I have built and configured several Dell systems with NVMe drives and from as far back as the 12th gen series where NVMe first started becoming available 2 CPU's have always been required, I believe this is due to the pci-e lanes required.  I am yet to see a Dell system that will allow NVMe drives that operate on a single cpu in the U.2 format anyway Dave
For our C6420 Blades with NVMes (U.2), when we run them with 1 CPU, they do not display the NVMes, but when we add a CPU (to make it 2 CPUs), they display just fine. I see nothing in the docs about these blades requiring 2 CPUs installed in order to display the NVMes, so I am wondering what may be the problem here. These are the standard NVMe C6420 blades being used in an NVMe capable C6400 chassis.
PE C6420 NVMe not Displaying with 1 CPU