
If your USB Port is not working, your SSD will not show up.

The same issue can occur with SanDisk and Crucial as well. A person bought a Samsung 840 EVO drive to upgrade, but the laptop doesn't detect the drive. SSD not showing up on Mac, whether it's new or used, is prone to happen for some reason. Launch Disk Utility > Select the grayed-out SSD located at the left. Mac external SSD not showing issues are caused by the system issues.

Connect the SSD with a different USB and check if the cable is working.
