In January I mounted a Crucial P3 Plus 4TB NVMe on a Raspberry Pi 5 inside an Argon Neo 5 M.2 case and moved everything onto it — Immich photo library, motionEye camera recordings, Docker volumes, a few databases, the odd SFTP sync target. It worked. Then it froze. A week later, it froze again. Then every few days. Then every few hours.
What followed was four months of hunting a ghost. If you are running a DRAM-less NVMe (P3 Plus, WD Blue SN580, Kingston NV2/NV3, HP EX900, many others) on a Pi 5, this post is written for you.
TL;DR. The Pi 5’s firmware disables Host Memory Buffer by default; DRAM-less drives need HMB to stay alive under load. There is no fix that makes a DRAM-less drive truly stable on a Pi 5 — only mitigations (HMB on, PCIe Gen 1, throttle stack) that reduce the wedge rate without eliminating it. The Practical Checklist below is the mitigation list. The full post is the four-month version of how I got there — and why the only real answer is to replace the drive with one that has on-board DRAM.