NVMe Device Specifications and Upgrade Requirements

2 8x4 Silent Gen4 PCIe® Card enables you to mount up to eight NVMe SSDs into a single x16 PCIe card slot and combine their capabilities for ultra-performance

2 is a slot that can interface with SATA , PCI Express

nvme vs m2 slot difference Some motherboards will only have one slot that can run at NVMe PCIe bandwidth, whereas others may be restricted to using SATA bandwidth

nvme 40 in 30 slot SATA is just a complete wasted slot ; all slots should be dual NVMESATA capable, or