Western Digital promises to introduce new model numbers from now on if the company adjusts an internal SSD and that change has consequences for the specifications of a product. WD is doing this after it turned out that the Blue SN550 was produced with slower nand memory.
In an email, WD admits to replacing the nand memory of the WD Blue SN550-NVMe SSD and updating the firmware. The company says that it has changed the datasheet of the SSD to indicate the other specifications, but gave little publicity about it. WD promises to be more transparent about this in the future when it comes to internal SSDs.
The Chinese site EXPreview was the first to write about the changed nand memory of the Blue SN550. According to EXPreview, previous Blue SN550 SSDs had a write speed of 849MB/s when the slc cache is full. However, the new SN550 models would only have a write speed of 390MB/s after the slc cache was full, which would be close to the Green SN350 when its slc cache is full.
It is not clear when WD took the modified SN550 into production. EXPreviews copy was produced on July 28. The site also notes that not all users will notice the slower write speeds. The slc memory of the NVMe SSD only fills up when files larger than 12GB are written.
WD is not the first manufacturer to quietly adapt the hardware of an SSD. For example, it was announced earlier this month that Crucial appears to be switching from tlc-nand to slower qlc-nand for the P2 SSD.