Today, Legit Reviews is taking a look at the HP SSD EX900 series of M.2 PCIe x4 NVMe 1.3 certified SSDs that just happen to be aimed at the entry-level market with capacities of 120GB, 250GB, and 500GB. The HP SSD EX900 drive series offers sequential speeds of up to 2100 MB/s read and 1500 MB/s write. Read on to see how the EX900 500GB drive performs!

The Silicon Motion SM2263XT PCIe Gen3 x4 NVMe 1.3 SSD Controller is new to us here at Legit Reviews, so we took a closer look at it. It turns out the SM2263XT has a DRAM-less design that supports the Host Memory Buffer (HMB) architecture. This means that the SSD uses your PCs DRAM to cache needed data (mapping tables) and you can visually see that in the block diagram below. That sounds scary at first. What happens when the power goes out or the drive is accidentally removed. It turns out the NVMe 1.3 specification was written to ensure the controller on HMB drives won’t have data loss or data corruption while the Host Memory Buffer feature is being utilized. Basically the controller writes updated mapping information to the HMB, but there is still a master copy on the drives NAND Flash before being flushed. This is said to have very little impact to CPU resources and and a tiny hit to the systems memory bandwidth and capacity. We tried to see how much memory was being used by this design and noticed about 0.3 GB less RAM being available on systems with 8GB and 16GB of system memory. Windows 10 began enabling this feature (Host Memory Buffer) by default with the Fall Creators Update and is not officially supported on older operating systems.