Can an M.2 NVMe SSD degrade after sitting unused for two years?

The SSD itself should be fine. Leaving it powered off doesn’t meaningfully use up its write endurance or shorten its lifespan. The bigger question is whether any data has lost charge over time, especially if the drive was stored somewhere hot or was already heavily worn. Two years at normal room temperature is unlikely to cause a modern TLC drive to suddenly fail, but you should still treat important files cautiously.

Boot the system and check the drive’s SMART or health information with a reputable utility. Look for critical warnings, media errors, unsafe shutdowns, percentage used, and self-test results. Make a backup of anything important before doing firmware updates or other maintenance. There’s no reason to replace the SSD solely because it sat unused for two years.

Flash memory can gradually lose stored charge while unpowered, but the risk depends heavily on NAND type, temperature, and the drive’s wear level. TLC generally retains data much longer than heavily worn QLC, and controllers may refresh older blocks when the drive is powered. A cool, lightly used drive is much less concerning than a nearly worn-out drive stored in high heat.

Anecdotally, many people have successfully used SSDs that were disconnected for several years. That doesn’t make them ideal archival storage, though. Once the computer is running, copy important data elsewhere and keep at least one additional backup. Replacing the drive is only warranted if diagnostics show errors, the data is unreadable, or the SSD has other signs of failure.