The WD Black SN850 is easily one of the best SSDs that money can buy right now. But owners had been reporting a performance loss over 40% when installing the SSD in a M.2 slot that's connected to AMD's X570 chipset. Fear not however, Western Digital has identified the problem, and the company tells us a solution is en route.
According to the manufacturer's investigation, the SN850 suffers from a drop in write performance on some X570 motherboards when the maximum payload size (MPS) is configured for 128 bytes. The option basically dictates the maximum transaction layer packet (TLP) that goes through the PCIe controller. Obviously, a low value will cripple devices with higher MPS capability, since they're forced to operate at lower MPS settings.
For now, it's recommended that SN850 owners install their SSDs on a M.2 slot that's connected directly to the Ryzen processor. If all your M.2 slots are already occupied, you may just have to wait for Western Digital's new firmware, which eliminates the MPS restriction on the SN850.
Western Digital assures us that the new SN850 firmware will be available for download on or before July 12, 2021. The update process is fairly simple, since all you have to do is launch the Western Digital Dashboard software, and it'll prompt you for the update.
You can find Western Digital's full statement to us below.
Western Digital's statement:
The WD_BLACK SN850 NVMe SSD can experience a decrease in write performance when connected to a chipset M.2 slot on certain motherboards, specifically when max payload size (MPS) is set to 128 bytes (128B). To resolve this issue, Western Digital will release a firmware update that eliminates a restriction in our product for this setting of MPS, expected to be available by July 12, 2021.
For optimum SSD performance, Western Digital recommends that customers download the latest BIOS version and drivers for their system and connect the WD_BLACK SN850 directly to the processor/CPU M.2 slot.
WD_BLACK SN850 customers can access/download the latest firmware via Western Digital Dashboard software. Once the firmware update is available, customers who open the Dashboard software will be prompted to make the update.