CompTIA A+ Core 1 (220-1201)HardwareHard
A technician installs a new M.2 SSD into a laptop, but the system does not detect the drive. Upon inspection, the SSD has a single notch positioned for an 'M' key, while the motherboard's M.2 slot is keyed for 'B+M'. What is the issue?
- AThe SSD requires a firmware update before it will be recognized
- BThe laptop's BIOS does not support M.2 devices at all
- CThe SSD's storage capacity exceeds the motherboard's limit
- DThe M.2 connector keying is mismatched between the SSD and the slot
Show answer & explanationAnswer & explanation
Correct answer: D. The M.2 connector keying is mismatched between the SSD and the slot
M.2 connectors use notch 'keys' (B, M, or B+M) that indicate which interfaces (SATA, PCIe x2, or PCIe x4) the slot and drive support. An M-keyed SSD requires a slot with an M or B+M key that also supports the matching electrical interface; if the physical or electrical keying doesn't align correctly, the drive will not seat or communicate properly.
Why the other options are wrong
- A. Firmware updates don't resolve physical connector keying mismatches.
- B. The scenario indicates a keying issue, not a total lack of M.2 support.
- C. Capacity limits would not prevent physical or electrical connection issues described here.
M.2 Connector Keying
M.2 slots and drives use notched keys (B, M, or B+M) to indicate supported interfaces like SATA or PCIe lanes; mismatched keys prevent proper installation.
- B key = up to PCIe x2 or SATA
- M key = up to PCIe x4 (NVMe)
- B+M key on slot supports both B and M keyed drives, but only up to the slot's actual lane support
Memory trick: B and M keys must match the lock, or the drive won't turn on