Western Digital and Samsung storage devices use different components than the first units sold and the ones received by the press for testing purposes.
In some cases, the difference implies a performance loss of up to 50% compared to the original models. More serious is that, for the consumer, both are the same model and there is no indication that they use different components.
The controversy began with Western Digital, when the Expreview site realized that the last units sold of the Blue SN550 M.2 NVMe used different NAND memories than the originals. That, by itself, is not surprising, and it happens very often; Sometimes a supplier cannot cover all the demand, so the company turns to a different one to obtain components with the same characteristics. Normally, although they are models or even different brands, these components fulfill the same functions and the user is not affected.
The real problem is that the new memories used by Western Digital are slower than the ones originally used, although it is not apparent at first. In short operations, where the SLC cache can be used, the speed of the WD Blue SN550 is spectacular, about 2,160 Mbps; But as soon as the cache fills up, throughput plummets to 390Mbps.
That’s similar to throughput with a lower-end WD Green SN350, which got 376Mbps. According to Expreview, the new WD Blue SN550 is 50% slower than the original in writing, figures that are very close to those obtained by Tom’s Hardware, which achieved 610 Mbps in a 100 GB copy test with the original model.
It is necessary to clarify that, if we do not ‘crush’ the SSD, there is not much difference; we are unlikely to fill the 12GB SLC cache and in that case performance is still good. However, if we work with files that occupy a lot, such as 4K videos, we will notice a drop in transfers. Above all, the worrying thing is that a change in performance was made without notifying users or the press , who published tests with the original version and generally recommended this SSD from Western Digital.
In response, Western Digital has confirmed that it changed the NAND memory of the Blue SN550 last June, but claims that at the same time, it changed the data sheet on its website. Still, you admit that more transparency is needed, and that in the future your model number will change when you make an internal change to your SSDs; however, it has not said anything about whether it will compensate users who have purchased the new version, hoping for performance they will never get.
Samsung would also be doing the same
Surprisingly, this is not the only such case discovered this week. Computerbase reports that a Chinese channel has discovered changes to the Samsung 970 EVO Plus , which are inconsistent with the original specification. In this case, you have changed both the 3D-NAND memory and the controller, which is from a different brand.
Another difference from Western Digital is that this change is not completely for the worse. It has a higher SLC cache of 115 GB, compared to 40 GB in the original model; as a result, performance is better with large files .
However, Samsung has not changed the name of this SSD; on previous occasions, it released V2 versions of its devices when implementing a similar enhancement. The reason is that the change also results in a loss of performance once the SLC memory is full; the original 970 EVO reached 1,500 MB / s in writing in that situation, while the new one does not exceed 800 MB / s.
At least, Samsung has changed the serial number, which is now MZVL21T0HBLU so if we look closely, we can avoid the new version; but it would have been better to have more transparency and better report on these types of changes, especially if they involve negative variations.