are all m 2 slots the same - Amazon.com: MACHINIST LGA 2011-V3 ATX Motherboard, X99 Gaming ... 888 slot 35

NVMe drives are exclusively compatible with the M.2 slot on a motherboard. It is essential to verify if your motherboard has any M.2 slots.

The Windows Task Manager shows "Slots used: 3 of 8": ... In the same time, CPU-Z shows that all 4 slots are present ...

M.2, PCIe, NVMe, it's all very confusing to me. From what I can tell to get the fastest boot speeds and data transfers M.2 storage drives are better than regular SSD's because the SATA connection bottlenecks the SSD's.