I bought a used Samsung 870 EVO and tested it in a USB enclosure before purchasing. CrystalDiskMark showed normal read and write speeds at the time. After installing it internally, the drive initially appeared only in CrystalDiskInfo, but formatting it and converting it to GPT made it usable.
I then transferred about 30 GB of videos and roughly 80 GB of Steam game files to it. A day later, the drive began showing 100% usage while streaming recorded gameplay, so I stopped using it for caching. Downloads and file transfers to the drive now stall around 0–2 MB/s, even with multithreaded Robocopy. A new CrystalDiskMark test showed about 600 MB/s read speed but only 8 MB/s write speed. CrystalDiskInfo also reports 48,534 CRC errors.
I replaced the SATA cable and tried another motherboard SATA port. After doing that, the drive tested at roughly 564 MB/s read and 384 MB/s write. Could the original cable or SATA port have caused the problem, or should I still be concerned that the SSD is failing or counterfeit?
3 Answers
A counterfeit SSD is still worth ruling out, especially because it was bought used. Samsung Magician may identify the drive and show its firmware and health information. You can also run a full-capacity write-and-read verification test, but back up anything important first because that test will overwrite the drive. Fake drives often appear normal initially and become extremely slow after their actual storage fills.
The original cable or SATA port could absolutely have caused the poor result, and the improved benchmark is encouraging. However, the earlier detection problem, severe slowdown, and CRC count mean I would not consider it trustworthy yet. Keep monitoring the SMART counters, test every part of the drive, and return or replace it if errors rise or performance drops again.
The CRC errors point more toward a SATA connection problem than the NAND itself. Since changing both the cable and port brought the write speed back to normal, retest it several times with the replacement cable and watch whether the CRC count continues increasing. Also check the motherboard’s SMART data and avoid storing anything important on the drive until it has passed extended tests.
I changed the SATA data cable and motherboard port, and the next test came back around 564 MB/s read and 384 MB/s write. I’ll keep monitoring the error count and verify the full capacity before using it for anything important.