NVMe SSD disappears after warm reboot but returns after shutdown
Environment
ASUS X670E motherboard with a PCIe 4.0 NVMe drive in the second M.2 slot.
What happens
A restart sometimes loses the data drive from BIOS, while a full power cycle restores it.
What I have tried
Updated the SSD firmware and checked drive health, which reports no errors.
I would appreciate advice on how to identify the root cause without risking existing data or configuration.
Verified community troubleshooting
The logs and behaviour point in the same direction here.
Likely cause: The motherboard firmware does not correctly reset the secondary M.2 controller on warm boot.
What I would try: Update UEFI, disable PCIe link-state power saving for testing and manually set the affected slot to PCIe Gen 4.
Document the original value before changing it and restore it if the symptom remains.
I had not considered that component. I will verify its state before replacing any hardware.