The ADATA Legend 840 is a solid-state drive in the M.2 2280 form factor, launched on November 3rd, 2021. It is available in capacities ranging from 512 GB to 1 TB. This page reports specifications for the 512 GB variant. With the rest of the system, the ADATA Legend 840 interfaces using a PCI-Express 4.0 x4 connection. The SSD controller is the IG5220 (RainierQX) from InnoGrit, a DRAM cache is not available. ADATA has installed 176-layer TLC NAND flash on the Legend 840, the flash chips are made by Micron. To improve write speeds, a pseudo-SLC cache is used, so bursts of incoming writes are absorbed more quickly. Thanks to support for the fast PCI-Express 4.0 interface, performance is excellent. The Legend 840 is rated for sequential read speeds of up to 5,000 MB/s and 3,400 MB/s write; random IO reaches 520K IOPS for read and 450K for writes.
At its launch, the SSD was priced at 101 USD. The warranty length is set to five years, which is an excellent warranty period. ADATA guarantees an endurance rating of 325 TBW, a typical value for consumer SSDs.