ASRock B450M Pro4: NVMe SSD not detected in M2_2

Confirm this is the original Pro4

This article applies to B450M Pro4, not Pro4 R2.0 or Pro4-F. Read the marking and use its manual. Also read the SSD's complete product number: M.2 is a form factor, not enough information about the drive interface.

The two storage sockets are different. M2_1 is the PCIe storage position; M2_2 is SATA-only and shares its connection with SATA3_3.

Choose the right troubleshooting branch

• PCIe NVMe in M2_2: check whether it can use the available, compatible M2_1 position. Software cannot turn this SATA-only socket into PCIe.
• SATA M.2 in M2_2: check SATA3_3 occupancy. The manual says these connections are mutually exclusive.
• A drive already detected by firmware: investigate boot or operating-system configuration separately.

Move hardware without losing the diagnosis

Record positions, shut down and disconnect mains before touching drives or cables. Follow the manual for standoff position and screw installation. Never force a module whose key or length does not match.

If M2_1 is occupied, plan what happens to that drive before swapping anything. After one change, return to firmware and check detection. Removing an operating-system drive can cause an expected boot failure, not a second hardware fault.

Protect the data and confirm the result

A drive with files should not be initialized or formatted just because it is absent from the file browser. Establish whether firmware can detect it through a compatible connection first.

If a compatible device is still undetected in the correct socket, check seating, model support and the drive itself. Keep the original specification as the authority; advice for a newer Pro4 revision may describe a different storage arrangement.

The useful outcome is a confirmed drive interface and a compatible available socket. That evidence should come before buying a replacement SSD.