Introduction

Lexar has made a name for itself in the portable storage market—they are very well known for their SD cards and USB drives, so it's natural for them to expand into other areas of flash storage, such as consumer SSDs. Lexar was founded as a subsidiary of Micron, but was sold to Longsys in 2017 and has been operating quite independently since.



Just a few weeks ago we reviewed the Lexar NM790 4 TB. While 4 TB is a ton of capacity, a lot of readers have been wondering how the 2 TB model performs. That's why we have the 2 TB model for review today. Just like the 4 TB model, the NM790 2 TB uses the Maxiotech MAP1602 controller that we've seen on drives like the Acer Predator GM7, Colorful CN700 and Netac NV7000-T. There's also no change in the flash chips, the NAND flash is 232-layer TLC, made by YMTC. There's just two instead of four chips. Just like on other MAP1602 designs, a DRAM cache chip is not included.

The Lexar NM790 is available in capacities of 512 GB ($45), 1 TB ($63), 2 TB ($110) and 4 TB ($190). Endurance for these models is set to 500 TBW, 1000 TBW, 1500 TBW and 3000 TBW, respectively. Lexar includes a five-year warranty with the NM790.

Packaging

The Drive

The drive is designed for the M.2 2280 form factor, which makes it 22 mm wide and 80 mm long.


PCI-Express 4.0 x4 is used as the host interface to the rest of the system, which doubles the theoretical bandwidth compared to PCIe 3.0 x4.


On the PCB you'll find the SSD controller and two flash chips. A DRAM cache is not available.


Lexar includes a preinstalled heat spreader foil with the SSD. We've seen this on other SSDs, too, but here the metal foil is rather thin. Still, as our thermal testing shows, this level of cooling is sufficient for everything except the worst possible scenarios.

Chip Component Analysis

MaxioTech's MAP1602A controller is produced on TSMC's 12 nanometer node and uses several Arm Cortex R5 CPU cores.


The four flash chips are YMTC 232-layer 3D TLC NAND.

Test Setup

Synthetic Testing

• Tests are run with a 20-second-long warm-up time (result recording starts at second 21).
• Between each test, the drive is left idle for 60 seconds, to allow it to flush and reorganize its internal data.
• All write requests contain random, incompressible data.
• Disk cache is flushed between all tests.
• M.2 drives are tested with a fan blowing on them; that is, except for the results investigating uncooled behavior on the thermal testing page.

Real-life Testing

• After initial configuration and installation, a disk image is created; it is used to test every drive.
• Automated updates are disabled for the OS and all programs. This ensures that—for every review—each drive uses the same settings, without interference from previous testing.
• Our disk image consumes around 600 GB—partitions are resized to fill all available space on the drive.
• All drives are filled with random data to 80% of their capacity
• Partitions are properly aligned.
• Disk cache is flushed between all tests.
• In order to minimize random variation, each real-life performance test is run several times, with reboots between tests to minimize the impact of disk cache.
• All application benchmarks run the actual application and do not replay any disk traces.
• Our real-life testing data includes performance numbers for a typical high-performance HDD, using results from a Western Digital WD Black 1 TB 7200 RPM 3.5" SATA. HDDs are significantly slower than SSDs, which is why we're not putting the result in the chart, as that would break the scaling, making the SSDs indistinguishable in comparison. Instead, we've added the HDD performance numbers in the title of each test entry.