My NVMe SSD used to be faster than my SATA SSD, but its performance has recently dropped significantly when tested with CrystalDiskMark. I've also noticed several problems lately: game shaders sometimes fail to appear, audio occasionally cuts out, the drive sometimes disappears from the computer until I restart, and some games crash. CrystalDiskInfo still reports the drive as 95% healthy, and download speeds from services like Steam haven't changed. The drive is a budget KingSpec NVMe model, and I'd prefer to avoid opening the PC unless necessary. Could the SSD be failing or corrupted, or might it be running at the wrong PCIe speed?
2 Answers
First check the link speed and negotiated PCIe mode for the NVMe drive. Also look for a firmware update from the manufacturer. A drive can still show a high health percentage while having connection, firmware, thermal, or controller problems. Since this is a budget drive and it has disappeared from the system before, back up anything important before doing more testing.
The 95% health result by itself doesn’t prove that everything is fine. Check the color and exact warning text in CrystalDiskInfo, along with the drive’s temperature and SMART error counters. You should also confirm whether the SSD is rated for PCIe 3.0 or newer and what speed it is actually negotiating at. BIOS settings, an incompatible slot, poor contact, or a firmware issue can force it into a slower mode. The disappearing-drive symptoms and crashes make a full backup especially important.
CrystalDiskInfo reports that the drive is healthy, and I believe it is a PCIe 3.0 model, although I’m not completely sure. I’ll need to check the detailed information to confirm the negotiated speed.

It’s a KingSpec NVMe drive, so I know it isn’t the best model. I ran benchmarks for both drives, with the SATA SSD listed as C: and the NVMe listed as A:, and the NVMe performed worse than expected.