Update 7/28/2016: There are finally more than a few NVMe drives for the consumer sector, and we've updated our picks. In particular, 1TB M.2 drives are now out, and price per GB has come down a bit since early 2016.
For decades, computer storage has been making huge strides in maximum capacities, but performance was falling far off the pace set by CPUs and GPUs. That all changed when flash-based solid-state storage (SSDs) hit the mainstream consumer market back in 2007. Those early drives were insanely expensive, and early adopters found that performance often degraded drastically over time, but they were the foot in the door.
By moving from the mechanical world of hard drives to the silicon world of SSDs, the industry experienced rapid improvements in performance, technology, capacities, and reliability. The SATA 1.5Gb/s bottleneck was quickly exceeded, followed by SATA 3.0Gb/s, and within a year of SATA 6.0Gb/s there were drives that could saturate even that interface. Faster alternatives were needed, but the interface was only part of the problem.
The other limiting factor was the command protocol, AHCI (Advanced Host Controller Interface), which was built to accommodate much slower media (e.g., spinning magnetic disks). AHCI ends up being inefficient when used with modern SSDs, and to get around these, a new standard was developed: NVMHCI (Non-Volatile Memory Host Controller Interface). NVM has 65K command queues with 65K commands per queue, compared to one queue with 32 commands in AHCI. It also has message signaled interrupts (MSI-X) and eliminates the need for synchronization locking when issuing commands. In short, it’s a much improved interface developed around the needs of flash memory rather than spinning disks.
NVMe drives do require motherboard BIOS support (if you want to boot from them), which generally means you need a relatively recent motherboard. Nearly all Z170 boards have NVMe BIOS support, and many Z97 and X99 boards will work as well. The latest motherboards also feature M.2 slots with x4 PCIe Gen3 interfaces, and this allows the use of an NVMe drive without taking up a lot of space. Just be aware that some boards (Z97 and X99 in particular) have M.2 slots limited to x2 PCIe Gen2 bandwidth, or 1GB/s, which will drastically limit the performance of the faster drives.
So, which NVMe SSDs are best? We’re skipping the enterprise-grade SSDs, as they’re far more expensive and if you’re in the market for that sort of drive, you should be running a server and will have a completely different set of requirements. 3.2TB with up to 743K IOPS, for only $8,000? Yes, please, we’ll take two. Quite a few new NVMe SSDs were announced at CES 2016 as well; we’ll update our recommendations as those launch and we’re able to test them. For now, here are the top three picks for consumer NVMe SSDs.
Best Overall NVMe SSD
- Excellent performance
- Decent price per GB for NVMe
- May throttle under heavy loads
- "Only" 512GB maximum
The number and capacity of M.2 NVMe drives has improved, which is great news for anyone with a recent desktop or laptop they're looking to upgrade. Prices are still much higher than SATA drives, but if you need the performance that only PCIe-based SSDs can provide, this is the road to the future.
Samsung was first on the scene with M.2 NVMe drives, and they still dominate the market. Their 950 Pro series delivers great performance in just about any workload, and Samsung has proven time and again that they know how to build a fast and reliable SSD. The 950 Pro 512GB is the current cream of the crop, sporting read/write speeds of up to 2,500/1,500 MB/s and 300K/110K random IOPS. We expect Samsung to begin shipping 1TB drives before the end of the year, probably sooner.
Samsung was also the first SSD manufacturer to utilize 3D stacked NAND, which Samsung calls V-NAND. The benefit of V-NAND over traditional planar NAND is that stacking (32 layers in early V-NAND, and now 48 layers in some cases) allows for more capacity in the same physical area, with only slightly increased volume—the layers are quite thin. Where this becomes useful is when using an older manufacturing process, 40nm in the case of current V-NAND.
Competing NAND solutions are now using processes as small as 15nm, but unlike CPUs and GPUs, for NAND smaller isn’t always better—in fact, in many ways it’s worse. Smaller transistors mean less ability to store charges in the NAND cells, and faster degredation of the substrate that helps isolate the charge. The result is that each NAND cell has fewer program/erase cycles before it stops working. By winding back the clock to 40nm, Samsung’s V-NAND offers a great balance of performance and capacity.
Best NVMe SSD for Desktops
- Fastest and highest capacity consumer NVMe SSD
- Works in any x4 PCIe slot and no throttling
- Uses a PCIe slot
- Needs NVMe BIOS to use as boot drive
M.2 is great for laptops and newer systems, but what if you’re using a desktop? Assuming you have a spare PCIe slot (at least a physical x4 connector), Intel’s SSD 750 SSDs were the first consumer NVMe drives to hit the market, and in many respects they’re still the fastest drives around. And unlike the Samsung 950 Pro, you can get far more capacity than 512GB—up to 1.2TB to be precise. For desktop users, our go-to NVMe SSD remains Intel’s SSD 750 1.2TB monster. Note however that you'll still need a motherboard with NVMe support if you want to use the SSD 750 as a boot drive.
Built from the same DNA as the company’s enterprise DC P3700, the SSD 750 is a consumer-focused drive with firmware optimizations that favor improved random I/O rather than maximum peak transfer rates. In practice, this yields better overall performance in some cases compared to the 950 Pro, but there are other instances where Samsung wins out.
Peak performance is rated at 2,500/1,200 MB/s read/write, with a whopping 460K/290K IOPS; for random write I/O, it’s hard to beat the SSD 750. The lower-capacity 400GB SSD 750 doesn’t perform quite as well as the 1.2TB model, and there’s also an 800GB model, but if you’re serious about NVMe storage we would stick with the 1.2TB drive. For those with the appropriate system, Intel offers the SSD 750 in a 2.5-inch form factor, using a U.2 (previously SFF-8639) connector. Those are as rare as hen’s teeth, particularly for consumer motherboards; while it’s possible to get an M.2 to U.2 adapter, in practice we’d stick with the PCIe add-in card models.
Best high capacity M.2 NVMe
- 1TB in M.2; enough said
- Very fast (nearly matches 950 Pro)
- 1TB carries a price premium
- Not widely available (yet)
Mention the name 'OCZ' to any hardware enthusiast and you're likely to get stories—some good, some bad, and everything in between. OCZ was one of the early entrants into the consumer SSD scene, and they made a big splash. Unfortunately, things didn't play out so well and in 2013 the company filed for bankruptcy. The good news is Toshiba acquired their assets and brand, and they're working to do things the right way. Post-acquisition, we've seen two wildly different SSD series bearing the OCZ brand. The Trion line is a budget series, and it's what you'd expect; the RD400 on the other hand…I hoped we would see someone compete with Samsung on M.2 SSDs, but I didn't expect it to be an OCZ drive!
The RD400 uses an in-house designed Toshiba controller, and the company has plenty of experience in creating reliable firmware—they're one of only a few brands of SSDs you'll find in big name laptops like those from Apple and Microsoft. But while Toshiba has been producing SSDs for OEMs for some time, they haven't usually been the fastest kid on the block—sometimes far from it. Ironically it's in a product that doesn't emphasize their brand that they finally have a real winner. The RD400 boasts specs that rival the 950 Pro in many areas, and what's more they have a 1TB model, and the cost per GB is generally better than Samsung on the lower capacity models.
Testing and other NVMe drives
The number of NVMe drives is still pretty limited, which means simply by virtue of existing they're worth a look. However, not all NVMe drives are created equal; our three primary choices represent the best an overall pick, the highest performance for desktops, and the highest capacity M.2 SSDs. Other drives exist but didn't quite make the cut.
We saw quite a few new NVMe drives at the last CES, and we're still hoping to see more competition on pricing. Toshiba's OCZ RD400 moves the price down slightly, but it's also not quite as fast as Samsung's 950 Pro, ending up as more of a tie. More M.2 drives should hit the shelves before the end of the year (we're still looking for the Patriot Hellfire and Kingston Predator NVMe, though Zotac did release an add-in card 480GB Sonix that seems to perform quite well), so we'll have to see what happens once the other SSDs ship.
Remember that the NAND chips make up a substantial portion of the total SSD price, and fundamentally there usually isn’t much of a difference between, for example, a SATA drive with 512GB V-NAND and an M.2 NVMe drive with the same 512GB V-NAND. NVMe requires a new controller and firmware, and there are associated R&D costs, but long-term NVMe prices should dovetail SATA SSD prices, with a moderate premium. Economies of scale are still a factor, however, so until more systems use NVMe SSDs, prices will stay higher.
Besides the drives we've recommended, we've also looked at other NVMe drives. Here's the complete list of NVMe SSDs that we've tested, in alphabetical order, along with a brief summary of results, with notes on the form factor: AIC (add-in card), M.2, or U.2.
Intel SSD 750 (AIC or U.2): The first consumer NVMe drive to hit the retail market, Intel's SSD 750 series is still a contender. Performance is excellent and in some areas it's the fastest drive. The main problem is that it's only available in two formats, as a PCIe x4 AIC, or as a 2.5-inch U.2 drive. Neither is suitable for laptop use, and U.2 support on motherboards is seriously lacking. There are some M.2 to U.2 adapters, though I'm not sure how well they work, and with the added cost you're better off just getting an M.2 drive. But if you have a U.2 port or want a PCIe AIC drive, Intel's SSD 750 has excellent sustained IO performance.
Samsung 950 Pro (M.2): Samsung's only current retail NVMe drive, the 950 Pro is arguably their best drive right now, and perhaps the best overall NVMe SSD. Combining 3D V-NAND with their in-house UBX controller, the 950 Pro has fast transfer speeds, great performance consistency, and it's supported by Samsung's Magician software. Slight throttling under heavy sustained loads is a minor concern, and one we've seen with other M.2 drives regardless.
Samsung PM951 (M.2): Is there such thing as an affordable NVMe drive? Samsung's PM951 happens to be the least expensive option, often by a rather large margin. Unfortunately, it's an OEM-only drive, so while you can find it online you won't receive any official support. Also, the drives use TLC NAND, and particularly on the lower capacity models performance ends up being no better than the faster SATA drives. But if you need one for a laptop, the 512GB model goes for around $200 on eBay.
Samsung SM951 NVMe (M.2): Samsung's first M.2 NVMe drive is still around, but it's mostly for OEMs meaning there's no direct Samsung support. Performance is actually pretty similar to the newer 950 Pro, and better in a few cases, but unless you get one of these with a laptop there's no particular reason to pick one up.
Toshiba OCZ RD400 (M.2 or AIC): Toshiba is the first to get a 1TB M.2 SSD to market, and the demand is high enough that the drives are currently priced above MSRP. The RD400 models aren't quite as fast as Samsung's equivalents, but they're also priced a bit lower, making them a reasonable compromise.
Toshiba XG3 (M.2): All indications are that the XG3 is the same hardware as the RD400, only it's a drive sold solely to OEMs. That means no direct warranty support and it's difficult to find for purchase. We did see one 512GB drive at Newegg through a third party, at a relatively low price, but the RD400 is a safer bet.
Zotac Sonix 480GB (AIC): A newly launched NVMe drive, Zotac uses Phison's new E7 controller. Phison used to be the whipping boy of SSD controllers, but since their S10 line came out in 2015, they've improved dramatically. The Zotac Sonix boasts some of the highest sustained transfer rates seen; unfortunately, random IO doesn't fare as well, and the limited options (the Sonix is only available as a 480GB AIC) mean it's a niche product.
As we separate the contenders from the pretenders over the coming months, we expect to see prices decrease on NVMe drives while performance continues to increase. Some of these drives are getting close to saturating even a PCIe x4 Gen3 link, which is awesome to think about. In practice, of course, many of these drives are pushing the storage bottleneck so far north that other components in your PC will become the limiting factor.