When Samsung and Western Digital secretly modify the components of their SSDs…

In the field of electronics, the change of components is nothing unusual: manufacturers regularly resort to it to deal with a shortage or to save a few dollars. In principle, as long as they do not drastically affect the performance of a product, these modifications go unnoticed; especially since some manufacturers do not bother to update the specifications. This is not the case with Samsung: the company has launched a new version of its SSD 970 EVO which is distinguished in particular by a new serial number. These changes caught the attention of a Chinese YouTube channel, whose tester decided to compare the performance of the old version of the 970 Evo Plus SSD in a capacity of 1 TB with the new one. Result: performance varies, with both improvements and degradations depending on the workload.

The old version, produced in April 2021, has the product number MZVLB1T0HBLR. It embeds a Phoenix controller [S4LR020] and 96-layer 3D TLC NAND memory (K9DUGY8J5B-DCK0). The most recent version, which resembles the 980 Pro, has the product number MZVL21T0HBLU. It swaps the Phoenix controller for an Elpis chip [S4LV003]. The SSD still inherits 96-layer 3D TLC NAND memory, but stamped K9DUGY8J5B-CCK0. The LPDDR4 DRAM used does not change. All of this data is compiled in the table below.

An SLC cache that goes from 40 GB to 115 GB

We now come to the results. The images on the left are of the original version; those on the right, revision. The new version of Samsung's SSD proves to be faster in workloads up to 115 GB. The reason is simple: HD Tune Pro shows that the revision has a larger SLC cache, 115 GB compared to 42 GB for the older version. However, once the SLC cache is filled, the revision suffers from significantly lower write throughputs. Indeed, while the original version achieves data write speeds of around 1,500MB/s after the first 40GB written, the revision tops out at 800MB/s after 115GB written. Well, nothing dramatic, since in the end, the new version completed the copying process a little faster.

Sharp decline in performance from Western Digital

If new buyers of a 970 EVO SSD will have nothing to feel wronged, the situation is very different on the side of Western Digital.

Again, the manufacturer has changed some components for its WD Blue SN550 NVMe SSDs marketed in Asia. According to Expreview, write performance outside of the SLC cache is plummeting. And unlike Samsung, Wester Digital has not extended the size of the latter (12 GB).

The 1 TB models produced for a few weeks would be armed with different memory chips: 002031 1T00 against 60523 1T00 previously. A change that would have an impact on write performance without cache: it apparently collapses at 390 MB/s. 1 TB version. The old 1 TB version of WD's SSD reaches 600 MB/s. In concrete terms, the revision delivers performance close to the entry-level model WD Green SN350.

Western Digital Response

Western Digital responded to these accusations by updating the random read and write performance of the 250GB, 512GB and 1TB models. Computerbase contacted WD to find out if these revisions were sold in Europe and more importantly, if customers had a way to know which version they were buying. Here is the company's response:

“In June 2021, we replaced the WD Blue SN550 NVMe SSD NAND and updated the firmware. At the same time, we have also updated the product data sheet.

In the future, when a modification is made to an existing internal SSD, we will introduce a new model number if the associated published specifications change. This will allow us to further increase transparency for our customers. It is important to us to provide our consumers with the best possible solutions for their data storage needs.”

Sources: Computerbase 1, Computerbase 2