What causes SSD not detected?
BIOS settings disabled the M.2 slot, firmware out of date, loose connection, wrong slot type (SATA vs NVMe mismatch), or defective drive. 90% of cases are connection or settings — not hardware failure.
Quick fix checklist (5 min)
1. Power down and unplug. 2. Reseat the SSD (pull out, reinsert firmly). 3. Try different M.2 slot if motherboard has multiple. 4. Check BIOS for 'M.2 disabled' setting. 5. Enable XMP/DOCP while you're in BIOS. 6. Restart and check again.
How to update BIOS for SSD compatibility
Visit motherboard manufacturer's support page, download BIOS file, put on USB, restart into BIOS setup (DEL or F2 key during boot), navigate to 'Update BIOS', select USB, confirm. Takes 5-10 minutes. Backup BIOS before updating. If this is NVMe on an older motherboard (pre-2018), BIOS update may add support.
Verify SSD in Windows (if partially detected)
Open Disk Management (Win+X), look for unallocated disk. If it appears there but not in File Explorer: right-click, Initialize Disk (GPT), create new volume, format NTFS. Now it'll appear in File Explorer.
When to seek professional help
If you've tried all steps and BIOS still doesn't see the drive after BIOS reset, the drive may be defective. Contact SSD manufacturer for RMA (warranty replacement). Usually ships new drive within 5 business days.