ASRock B550M Pro4: M2_2 or SATA 5/6 disappears

Make a storage inventory

List each drive, interface and connector. Distinguish M2_1 from M2_2 and the separate wireless Key E socket, which is not an SSD position.

The manual specifies M2_2 for a 2280 SATA module or PCIe storage up to Gen3 x2. That lower PCIe link is part of the board design, not automatically evidence of a defective SSD. Actual compatibility still depends on the device and configuration.

Resolve the port conflict first

1. Shut down and disconnect mains before moving hardware.
2. Locate SATA3_5 and SATA3_6 from the labels and layout.
3. To retain a compatible SSD in M2_2, move affected SATA data cables to free supported SATA3_1–4 ports.
4. Check firmware detection after reconnecting power. Keep track of the operating-system drive.

Detection and speed are different questions

If the drive appears but benchmarks below its advertised maximum, compare the socket link with the drive specification. A PCIe x2 connection has fewer lanes than x4. Workload and the rest of the system also affect performance; an interface maximum is not a promised benchmark.

Do not blindly change RAID or storage modes. Such changes can affect an existing installation and do not remove the sharing rule.

When the conflict is not the cause

If SATA3_5/6 are unused and a compatible M2_2 device remains missing, investigate interface, module length, seating and firmware support. If firmware sees it but Windows does not, follow that different branch.

Preserve data. Initializing a disk is not a general repair for a missing volume. Record the final working ports so a later upgrade does not recreate the same conflict.

When requesting support, include the full drive model and every occupied storage connector; a bare description of “two M.2 drives” omits the information needed to diagnose this board.