I'm copying an Elden Ring installation between folders on the same 2TB Crucial P3 NVMe SSD in Windows 11. Large files initially transfer at roughly 500–600 MB/s, but the speed repeatedly falls to 0 B/s. While this happens, other applications—including games—can freeze for 5–7 seconds and show "Not responding," and even pausing the copy takes several seconds.
The same 20GB file copies consistently at over 800 MB/s on my Samsung NVMe drive. I understand that the Crucial P3 uses QLC NAND while the Samsung uses TLC, but CrystalDiskMark also reports unusually low sustained write speeds of only about 90–100 MB/s on the Crucial, compared with roughly 3 GB/s on the Samsung. Read speeds look normal.
The Crucial drive is about seven months old, has around 500GB free, and CrystalDiskInfo reports good health with no critical warnings or integrity errors. Temperatures also look normal. Enabling Momentum Cache makes synthetic benchmark numbers exceed 7 GB/s, but real-world copying still fluctuates between about 140 and 500 MB/s and sometimes drops to zero. Is this expected behavior for a QLC drive, or could the SSD or another component be failing?
4 Answers
The AMD platform theory is not enough by itself, especially since this is an AM5 system. First isolate the SSD by testing it in another M.2 slot or another computer, and check Event Viewer for disk, storahci, stornvme, or WHEA errors. If the same drive produces the same stalls elsewhere, the SSD is the leading suspect; if not, investigate the motherboard slot, BIOS, and chipset software.
Make sure the drive has plenty of additional overprovisioning space and test it while the system is otherwise idle. Copying files within the same SSD means the drive is reading and writing at the same time, which is harder on an inexpensive QLC model than a simple sequential write test. A temporary drop is normal, but repeated zero-speed periods that freeze unrelated programs could indicate firmware, controller, or drive problems. Keep backups and consider replacing the drive under warranty if the behavior remains after firmware and platform checks.
The most likely explanation is that the drive’s fast SLC cache is being exhausted. QLC drives can write quickly for a while, then fall dramatically once the cache is full—sometimes to around 100 MB/s or lower while the data is folded into QLC storage. Large 11–13GB files can expose this behavior much more than ordinary desktop use. The pauses happen because the SSD is busy internally and Windows is waiting on I/O, although severe system-wide freezes are still not ideal.
QLC alone doesn’t prove the drive is defective, but 90–100 MB/s sustained writes and long stalls are worth investigating. Check the P3’s firmware, motherboard BIOS, NVMe/chipset drivers, PCIe link speed, and Windows storage errors. Run a sustained write test with enough data to exceed the cache, not just a short benchmark. Also compare results with Momentum Cache disabled; its benchmark scores mainly measure RAM caching and it can risk losing recently written data during a crash or power failure.
There’s still about 500GB free, so it doesn’t seem nearly full. The drive is also only around seven months old.