RAID 0 and 1 both require 2, RAID 5 uses 3. There are no other configurations.
the KB article Intel Rapid Storage Technology can only detects 3 NVME SSDs on the Precision 7730 states that only three of the four available NVMe slots can be used to setup a RAID with Intel RST on a Dell Precision 7730. Does this limitation also apply to the Dell Precision 7740? I cannot find relevant information in the Dell Precision 7740 Setup and specifications guide.
maximum number of NVMe slots usable for RAID on Dell Precision 7740