Lexar NM790 4TB SSD evaluation

With the rising calls for of right this moment’s trendy video games, and the propensity for these video games to demand speedy solid-state storage, the demand for 4TB NVMe SSDs is understandably hovering. I’ve obtained excellent news for you, as properly. These 4TB drives aren’t all that costly anymore, as confirmed by this glorious Lexar NM790, which is able to set you again simply $200/£185 (typically much less).

To place that worth into perspective. The Lexar calls for 5 cents of your hard-earned money per gigabyte. Indulge me for a second as I flick by our historic check knowledge. You’d have paid round $41 cents per gigabyte of SATA velocity storage again in 2013. It is actually mind-boggling how low cost SSDs have grow to be over the previous ten years.

This Lexar NM790 is way faster than some previous SATA SSD from our archives. Rated to 7,400MB/s sequential reads and 6,500MB/s sequential writes, it is fairly near as quick as its Gen4 PCIe interface will enable. In my very own testing, I measured it at 7,106MB/s seq. learn and 6,504MB/s seq. Write—very practically bang on what’s marketed, which is de facto nice.

It is also fairly speedy in random workloads, which is able to make for a snappier system. It is available in at 75MB/s learn and 291MB/s, which is within the combine with among the sooner Gen4 and first-wave Gen5 drives we have examined.

For a DRAM-less drive, these are all very spectacular numbers.

The Lexar does differ from many others we have checked out. We have come to count on higher-end Gen4 drives to depend on Phison’s highly regarded E18 controller, however the Lexar does not. It makes use of a MaxioTech MAP1602A controller, a much less recognized amount within the US and EU markets. This makes for overtly totally different behaviour in testing to extra widespread controllers, however not in a foul means.

For one, this drive is cool beneath load. Whereas copying our 30GB check folder—a reasonably intensive workload—I measured it at solely 57°C max. That is just about its base stage with an ambient temperature of round 23°C. When transferring over 200GB of knowledge in a single regular stream, which you will not do all that usually in real-world use, I measured the temperature at 72°C. That is an admirable temperature from a drive with no lively cooling resolution and excessive speeds.

The NM790 makes use of SLC caching to succeed in its marketed write speeds. Most trendy drives will use some kind of SLC caching to hurry up preliminary file transfers, because the native NAND expertise will not be capable to sustain. This implies the SSD will function a few of its triple-layer cell (TLC) or quad-level cell (QLC) NAND as single-layer cell (SLC) NAND. The reason is SLC is way faster than TLC or QLC, although shops much less knowledge per cell. As soon as a file switch is accomplished, the SSD will begin shifting the information from SLC cache to TLC NAND, releasing up the SLC cache for additional transfers. Nonetheless, if the file switch exceeds the dimensions of the obtainable SLC cache, the drive will resort to utilizing the slower NAND as a substitute.

The NM790 makes use of 232-layer TLC NAND manufactured by YMTC. It improves on this with a big SLC cache buffer, made attainable as a consequence of its massive general capability. We will check simply how briskly the SLC cache and this native TLC NAND is with a easy IO check.

I’ve thrown a big, steady stream of knowledge on the NM790 and plotted the information to the chart beneath. The quick preliminary switch of round 6,400MB/s is the SLC caching at work. The next drop-off across the the 100 second mark is the second when the faux-SLC cache is expunged and the drive is writing to its TLC NAND as a substitute. Whereas considerably slower than SLC, the TLC NAND on the NM790 is not terribly sluggish itself, managing round 2,500MB/s.

It is also attainable with this check to search out how a lot of the Lexar’s 4TB capability is ready for use as speedier SLC cache earlier than it defaults to the native TLC. The NM790’s efficiency dipped after I would written round 642GB of knowledge to the drive in a single regular write switch, that means round 16% of the drive’s complete 4TB capability is obtainable as speedier cache. Because the drive fills up that SLC cache measurement will cut back, although with a 4TB drive you’ve got loads of room to play with earlier than that happens.

What’s vital is you should not need to resort to the TLC NAND speeds all that usually. Even right this moment’s largest video games do not come near 642GB in measurement, and it is unlikely you will be transferring this quantity with none breaks between—give the SSD some respiratory room and that SLC cache will bounce again to full efficiency.

I had thought we would actually hit the utmost potential for PCIe Gen4 drives with the final wave of SSDs. Contemplating the primary wave of Gen5 drives are right here, most enjoyable new developments in controllers and NAND are being leveraged for that speedier interface. But the Lexar proves in any other case. A excessive capability SSD that performs simply in addition to a lot of right this moment’s high Gen4 NVMe SSDs, for much less money. 

If in case you have a spare Gen4 slot in your machine, and you’re determined for extra sport cupboard space, I extremely advocate you look to the Lexar NM790 to fill that slot.