Of course we have the M.2_1 and M.2_2 slots on the Mobo. But what about a add on PCIE expansion card for M.2?
I am running a 970 Evo in M.2_1 and a 960 Evo in M.2_2 now along with 5 SATA drives. I am running the 960 Evo in X2 mode to keep all my SATA ports available. Yes, I have a lot of drives.
Research has told me that you cannot run more than 2 PCIE (NVME) M.2s on this board. Yet it appears to be working partially. I can see all 3 NVME drives. I can write and read from all of them. I can run AS SSD tests on all of them and they all run at at least NVME X2 speeds.
What I can't do is create a RAID 0 from the drive in M.2_2 and the PCIE X8 slot. IRST will recognize all the drives but the PCIE expansion slot. AOMEI and EASUS and Win 10 will recognize all 3 of my NVME drives and all 5 of my SATA drives.
So I can live with this, but would like to combine the two 1TB NVME drives to a 2TB fast RAID 0. My OS drive is a 970 EVO in 2TB.
Let's see if I can pass on my findings. Actually the Z370-E will handle 3 NVME drives in PCIE slots. Two in the M.2_1 and 2 slots. And one in an PCIE expansion card. And they will operate at NVME/PCIE X2 speeds. And yes you can RAID 0 two of the drives. In my case the drive in M.2_2 and the one in the add in card.
However as others have said the RAID Drive is actually a bit slower than the two drives are as separate drives. To give you an idea, Acronis TIB takes 90 minutes to back up my 850 GB OS drive to a SATA SSD. It took 70 minutes to back up to the NVME RAID 0 array and takes 45-50 minutes to backup and validate the 850 GB OS drive directly to either of the drives set up as discrete NVME drives. The Benchmarks support that observation.