Everyone in the inner circle of the SSD world is buzzing about the successor to Samsung's 950 Pro NVMe. We already tested the Samsung SM961 several times in the past, and it should be representative of the new 960 Pro. The low-cost EVO variant is even more exciting because it features the same Samsung Polaris controller and DRAM as the SM961 but uses 48-layer 3-bit per cell (TLC) flash. We're testing the PM961, which is the TLC version of the SM961, and likely the close cousin to the 960 EVO that will possibly launch in the next month.
Since its inception, the EVO series has dominated retail sales. Samsung actively monitors the price of competing products and maneuvers the EVO models appropriately, so the EVO products often cost a little more compared to entry-level and mainstream products. The strategy only works because the EVO series typically delivers significant improvements over competing products.
The improvements are not just performance-based, although it plays a key role. Samsung delivers an all-round package with higher performance, best-in-class software packages, high availability (products sold in local retail stores) and excellent reliability. It's difficult for non-fab SSD manufacturers to compete with Samsung's all-bases-full strategy. Even fab competitors (those that make NAND flash) that aren't fully vertically integrated (the ability to make controllers, DRAM and NAND flash) have a hard time competing with Samsung.
Samsung's big advantage isn't just its crafty strategy, accessories or price; it's the flash. Samsung was the first to release retail products with 3D NAND, and its dual plane design maximizes parallel operations to the controller. Until the PM961, we didn't know how fast Samsung's TLC V-NAND really was because the SATA ceiling limited most of its products. The PM961 will finally give us a chance to see if Samsung's 3D NAND has a lead over IMFT's (Intel/Micron) new 384Gbit TLC 3D NAND.
|Form Factor||PCIe 3.0 x4 M.2 Single-Sided 2280 |
|NAND||Samsung 48-Layer TLC V-NAND|
|Available Capacity Sizes||128GB, 256GB, 512GB, 1TB|
|Sequential Read||Up To 3,000 MB/s|
|Sequential Write||Up To 1,150 MB/s|
|Random Read||Up To 360,000 IOPS|
|Random Write||Up To 280,000 IOPS|
|Warranty||Varies By Seller|
We still don't know a lot about the Polaris controller, other than the fact that Samsung uses it in the fastest consumer NVMe SSD ever made (the SM961). The PM961 uses the same controller and low-power DDR3 DRAM as the SM961, but Samsung changed the flash from 2-bit MLC to 3-bit per cell (TLC) V-NAND. Samsung's 3rd generation V-NAND is somewhat special and comes with a 48-layer 256Gbit die. Samsung designed the flash to reduce manufacturing costs by ramping up the capacity within roughly the same wafer footprint. Samsung's 48-layer NAND has been successful, but the company already announced the technical details of its 60-layer successor. Samsung's next generation NAND provides 512Gbit of capacity per die, but we don't expect products with the new V-NAND to ship until 2017.
Just because we know about the next generation doesn't mean we should overlook the importance of the current 48-layer flash. Only a few retail products have shipped with the 48-layer 256Gbit die. Samsung launched the Portable SSD T3 this year, retooled the higher capacity 850 EVO SSDs, and slowly trickled out the SM961 with the new flash. The PM961 is only the fourth product we've tested with 48-layer V-NAND.
The only PM961 performance specifications we have come from a Samsung event held earlier this year in Japan. The specifications in the chart come from a place card pictured at the event, and we don't have specifications for individual capacities or endurance. We do have the PM961 512GB, which will give us a taste of what Samsung has on the grill.
Samsung used new multi-manager test methods to achieve the high performance values cited in its specifications. We still use industry-standard testing that is more representative of normal user workloads, so you shouldn't expect to see 3,000 MB/s in our tests. We used multi-manager test methods only to validate Samsung's claims, and we actually achieved slightly better performance. The PM961 is impressive with 3,000 / 1,500 MB/s of sequential read/write speed. The random read performance surpasses 360,000 IOPS, and random writes are not far behind with 280,000 IOPS. On paper, the PM961 appears to give the 950 Pro with 32-layer MLC V-NAND a run, but in practice, the additional TLC latency hinders performance. Still, this high-performance product will eventually make an excellent mainstream NVMe SSD for shoppers looking to break free from the bonds of SATA. It will come at a friendlier price point, too.
The PM961 also supports several advanced features. The drive can operate in L1.2 low power states and employs TurboWrite technology, which is an SLC-mode buffer that absorbs random writes to increase performance and reduce flash wear. The PM961 does not support some features that we expect from the retail model, such as Rapid Mode and full-disk AES hardware encryption.
Pricing, Warranty And Accessories
Securing a PM961 isn't easy, but you can find them for $549 with a lead-time of 1 to 2 months. We paid $313 for a PM961 512GB to make this 960 EVO preview possible. Our drive took just over a week to arrive, and there isn't a warranty to speak of, though we did get an M.2 screw with the drive as a consolation prize. Some notebooks do not include the M.2 screw, particularly if you order the system without an M.2 SSD.
We don't recommend buying a PM961 because the price is very high due to the limited availability. The OEM products also do not work with Samsung's Magician Software. This isn't much of an issue, but with the 960 Series so close to launch, we would wait another month and compare the OEM SSDs to the retail products. The retail versions, which will presumably come to market bearing 960 Pro and 960 EVO branding, will work with Magician. The 960 EVO may include access to Rapid Mode, which is a system-level RAM buffer that increases performance and reduces NAND flash wear. Samsung's retail SSDs also work with the company's disk cloning software. The big takeaway is the Rapid Mode software and easy access to Samsung's NVMe driver, which we will cover later in the review.
A Closer Look
The drive doesn't offer us a lot of insight into the new PM961, or its potential 960 EVO retail counterpart. The SSD appears to be identical to the SM961 that we already tested, and it features the same controller and DRAM. The Polaris controller is at the heart of the SSD and Samsung LPDDR3 backs it up. Two packages of Samsung 48-layer TLC flash round out the major components, and each package contains eight 256Gbit (32GB) die stacked on top of one another.
The PM961 uses a single-sided design to increase compatibility with OEM designs. The single-sided design features all of the surface mount components on one side of the printed circuit board, which allows OEMs to place the drive closer to the motherboard, and thus design slimmer products. Eventually, many of the slim products will get a storage upgrade, but the dual-sided products will not work in some of them. We've already seen a Lenovo Carbon X1 with the issue. The Lenovo motherboard has another chip package under the M.2 area, so it is impossible to install a dual-sided M.2 SSD and reassemble the case.