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Review: Corsair's Neutron and Neutron GTX solid-state drives

— 11:03 AM on October 11, 2012

In the world of solid-state drives, Corsair has a reputation for, well, getting around. The enthusiast-oriented component maker has hooked up with all the big names in the controller business: Indilinx, Marvell, SandForce, and Samsung. It even had a tryst with JMicron, a dalliance that can probably be blamed on a combination of alcohol and low self esteem.

Corsair's willingness to experiment with controller technologies has allowed the company to hedge its bets, offering multiple product lines based on different solutions. The Force series has used the latest SandForce controllers, while the Performance line has featured Marvell silicon. The Indilinx-based Nova model still serves the budget market to this day, and there are Accelerator drives designed for caching, too.

All of those drives are part of a diverse family of offerings, but none of them are really unique in the wider context of the market. The fact is, everyone and his mother is making SSDs these days. Most vendors, Corsair included, are pulling from the same limited selection of NAND, controllers, and stock firmware.

Corsair's Neutron SSDs are different, though. They're the first and thus far only drives on the market using Link_A_Media Devices' new LM87800 controller. Corsair has exclusive access to the controller right now, and it has deployed the chip alongside two flavors of NAND memory in the Neutron and Neutron GTX. We've tested both to see how they stack up against not only each other, but also their peers. Before diving into those results, let's meet Corsair's new muse.

Inside the Neutron
Based in Santa Clara, California, Link_A_Media Devices got its start in 2004 and specializes in storage-related SoCs. Yes, those are underscores in the name—how edgy. To avoid having to type them constantly, I'm going to refer to the firm as LAMD. Besides, the company has sold out already. LAMD was acquired by memory maker SK Hynix earlier this year, not long after the then-upcoming Neutrons were announced as the first consumer-grade SSDs based on LAMD controllers. According to Corsair, LAMD SSD silicon was previously used only in enterprise-class products.

Both Neutrons rely on the same LAMD LM87800 controller. This chip features dual ARM processor cores, one dedicated to the host and the other to the NAND. On the host side is a 6Gbps Serial ATA interface. On the flash side, the chip supports NAND from the ONFI and Toggle DDR camps.

LAMD is quick to tout eBoost, a combination of error correction and "adaptive signal estimation techniques" that purportedly enables the LM87800 to extend the endurance of both kinds of NAND. There's no SandForce-like write compression involved here, just advanced signal processing. eBoost promises enterprise-class reliability for client SSDs, including those based on the upcoming 1x-nm generation of flash memory.

The LM87800 also has a built-in redundancy scheme that protects the drive from physical flash failures. Storing redundancy data requires some extra capacity, which explains why the Neutrons come in 120GB and 240GB sizes rather than the more traditional 128GB and 256GB. Corsair has a 480GB version of the GTX in the works, as well, and the controller supports up to a terabyte of flash.

Model Max sequential (MB/s) 4KB random write (IOps) Price
Read Write
Neutron 120GB 555 211 80,000 $120
Neutron 240GB 555 370 85,000 $210
Neutron GTX 120GB 555 330 80,000 $140
Neutron GTX 240GB 555 511 85,000 $250

Like its contemporary counterparts, the LM87800 has eight memory channels. Each channel can connect to up to four chips, allowing the controller to address a maximum of 32 individual NAND dies. The 240GB Neutrons tap that full capacity, serving up at least 32 NAND dies each. With fewer NAND connections, the 120GB models can't take advantage of as much controller-level parallelism, which is why their write performance ratings are lower. The drops in claimed sequential write throughput are much larger than the small dips in 4KB random write performance.

As the write performance ratings clearly illustrate, the standard Neutron is slower than the GTX. The Neutron uses ONFI-compliant synchronous NAND from Micron, while the Neutron GTX relies on Toggle DDR flash made by Toshiba. The memory chips for both come from 2x-nm nodes: the Micron stuff is fabbed on a 25-nm process, and the Toshiba chips are built using 24-nm tech.

The Micron NAND has two 64Gb dies per package, which means the Neutron needs 16 individual packages to offer 240GB of total capacity. Corsair splits the NAND evenly between the two sides of the Neutron's circuit board. With eight 32Gb dies in each of its Toshiba flash packages, the GTX can hit 240GB while populating only one side of the circuit board with eight islands of NAND.

We're used to seeing 8-16 NAND packages on SSDs of this capacity. However, we're not using to seeing the flash laid out on such stubby circuit boards.

The circuit boards on both drives are about 20% shorter than usual, as evidenced by the leftover space inside the Neutrons' enclosures. Incidentally, the cases eschew the screws used by most SSDs in favor of snap-on covers that probably save a cent or two. If you want to see the Neutrons in the nude, the covers can be pried off using a flat-head screwdriver. Amusingly, doing so won't disturb the warranty stickers covering the screw holes on the undersides of the drives.

Corsair offers five-year warranties with both Neutrons, equaling the best coverage we've seen among consumer-grade SSDs. Three-year warranties are more common, and the extra coverage will surely help to justify the Neutrons' asking prices. The GTX is notably more expensive than some of its direct competitors, which have equivalent capacities but cost $200 or less.