Which Slot to use?

NVMe SSD 50% slower on socket 1 nvme m 2 slot Okay, that board supports NVMe drives in all three slots If I were you, I'd diagnose further by trying the 3rd slot, or swapping into nvme m2 slot Advanced Thermal Design with Enlarged Surface Heatsinks; Ultra Durable™ PCIe x16 Slot; Dual Ultra-Fast NVMe PCIe x4 with Dual Thermal Guards

nvme slot Non-Volatile Memory Express drives attach to the Peripheral Component Interconnect Express slot directly on a motherboard instead