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
There aren't too many options for consumer NVMe SSDs right now, and even fewer choices if you want an M.2 form factor. This can be particularly important if you want a fast SSD for a laptop, with many slim laptops only offering M.2 slots these days. For now, the first and only retail M.2 NVMe drives are Samsung's 950 Pro drives, though we should see several more in the coming year. As one of the biggest names in the SSD market, 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.
Samsung is the first SSD manufacturer to utilize 3D stacked NAND, which Samsung calls V-NAND. The benefits of V-NAND over traditional planar NAND is that stacking (32 layers in the current V-NAND) 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, with the result being 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.
Our review of the smaller 256GB drive found a lot to like, but doubling the capacity has several benefits. There's the obvious one of having twice as much storage, and for power users we're at the point where 500GB-class SSDs are as small as we're willing to go—and presumably anyone who really needs the speed of an NVMe drive will also want more than 256GB of capacity. The other benefits come from the improved parallelism that additional NAND packages offer. NAND chips read and write data pretty quickly, but the real speed in SSDs comes from having many NAND chips reading/writing simultaneously. With twice as many NAND chips (there are multiple chips per package), the 512GB 950 Pro ends up being moderately faster than the 256GB model.
Our review will be posted soon, but overall the 512GB model is around 20 percent faster than the 256GB model across our test suite, with write speeds in particular favoring the larger drive by 50 percent and more. And as a final bonus, where the 256GB model costs $190, the 512GB model costs $330, making it the least expensive NVMe SSD in terms of price per GB. Though it's at an admittedly still high $0.64 per GB, it's over twice as expensive as Samsung's 500GB 850 Evo… and much more than twice as fast.
There is one potential cause for concern with the 950 Pro drive, and that's thermal throttling. In short, the amount of data that the drive and controller can process in a short amount of time is staggering. Under heavy loads, however, it can cause the controller to heat up to the point where it has to reduce clock speeds in order to keep temperatures in check. For normal workloads, this doesn't happen much and even when it does it's not particularly noticeable. However, it's worth considering cooling the 950 Pro—why spend top dollar only to potentially lose 10 percent of the maximum performance? In our testing, simply directing a fan at the drive was enough to eliminate throttling, and some motherboards come with built-in cooling for their M.2 slots. It's not a deal-breaker by any means, but you'll want to factor in SSD cooling during the build process.
Best NVMe SSD for Desktops
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), there are other drives available. In fact, 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—1.2TB to be precise. For desktop users, our go-to NVMe SSD remains Intel's SSD 750 1.2TB monster.
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 now, 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.
Going with a much larger device, plus the use of a rather hefty heatsink, means throttling isn't a concern with the SSD 750. However, the drive isn't as energy efficient as other SSDs, being built for speed rather than power savings. Where M.2 SSDs can go into low-power modes that use less than 100mW, the SSD 750 idles at 4W and uses as much as 22W under load. That would be a deal-breaker in a laptop drive, but on a desktop it's far less a concern. The only problem is that you still have to find a spot for the drive on your motherboard, which can be a bit tricky on SLI and CrossFire rigs, not to mention you'll want to ensure you have enough PCIe lanes available to prevent bottlenecks.
Pricing on the SSD 750 has improved since the drive first launched in April 2015. Originally available in just two capacities, 400GB and 1.2TB, MSRPs were $389 and $1,029, or just shy of $1 per GB. Today, the 400GB model costs $350, the more recently introduced 800GB drive costs exactly twice as much at $700, and the 1.2TB drive has dropped to a current sale price of $850. That yields a final price per GB of $0.71, which is higher than the above 950 Pro 512GB but still acceptable for a high-end NVMe SSD.
Some final food for thought is that Intel's DC P3700 is now eighteen months old, and the SSD 750 is nearly a year old, which is a long time in the technology sector. Since then, Intel and Micron announced availability of their 20nm 3D NAND; the chips haven't shown up in any SSDs to date, as everyone is currently in the testing and validation phases, but that should change soon. The first drive rumored to use IMFT's 20nm 3D NAND is Intel's DC P3520, which will be an enterprise-class SSD; hopefully, we'll see a consumer equivalent sooner rather than later. It will be interesting to see how the performance of the IMFT 20nm 3D NAND compares to Samsung's 40nm V-NAND, but one advantage for IMFT is that the 32 layers provide 256Gbit per die, with up to 16 die in a single NAND package. That would allow for up to 2TB M.2 2280 SSDs using four such packages, or twice the maximum capacity of Samsung's current V-NAND.
Best Entry-Level NVMe SSD
Is there really such a thing as an "entry-level" NVMe SSD? Frankly, no, there's not—the least expensive drive is the little brother of our primary choice, the Samsung 950 Pro 256GB. You have to give up half the capacity in the process, but for less-demanding users 256GB may still be sufficient. Due to the decreased parallelism, this model is also going to be a bit slower in peak performance compared to the 512GB drive. It's rated at 2,200/900 MB/s read/write, with 270K/85K IOPS. The good news is that it's still extremely fast, and it also costs less than $200 ($190 at the time of writing).
You can read our full review of the drive, but most of what we said about the 512GB drive applies here. Rather than focus on detailing the minor differences between the 256GB and 512GB models, let's talk about a few of the other NVMe SSDs that we eliminated from the list and explain why they didn't make the cut.
Outside of enterprise-class NVMe SSDs (which, again, start at well above $2 per GB—you wouldn't really want to pay more for the 400GB P3700 than you'd spend on the 1.2TB SSD 750, right?), the only other NVMe drives presently available come from Samsung. There are actually two options here, the SM951 NVMe (which we reviewed in 256GB form), and the PM951 NVMe. Both of these are sold as OEM drives rather than retail drives, which means you'll find them in quite a few laptops. However, Newegg stocks the SM951 NVMe now, though it's offered via a third party and comes with a third-party warranty; the PM951 NVMe, meanwhile, is a bit more difficult to find (it's on Amazon in limited quantities). So, what's the difference between these drives?
Besides the warranty issue, the SM951 NVMe is actually a very fast drive—sometimes a hair faster than the 950 Pro. It uses planar MLC NAND instead of V-NAND, which isn't necessarily good or bad. The biggest drawbacks are pricing, availability, support, and warranty. Simply put, the 950 Pro has supplanted the SM951 NVMe in all cases. The 128GB drive might be worth a look if you only need a small SSD, but we have a very difficult time fitting all of our files onto such a capacity, plus it will inevitably perform worse than the 256GB model (decreased parallelism again, only it's more noticeable when dropping to 128GB vs. 256GB). And at more than $1 per GB, it's definitely not a bargain.
The PM951 NVMe is much more interesting from a pricing perspective, going for $74 for 128GB, $130 for 256GB, and $255 for 512GB. What's the catch? Simple: PM951 NVMe uses TLC NAND, resulting in a pretty serious drop in performance relative to the MLC SM951 and 950 Pro. According to the specs tables, the 128GB model is only slightly faster than a good SATA drive (600/150 MB/s read/write speeds, with 140K/37K IOPS). We've actually encountered this drive in a laptop, and while it wasn't horrible, it didn't really impress either. The 256GB and 512GB models are better, but they're still only half the transfer speeds of the 950 Pro. In short, you get what you pay for.
If we could get Samsung's usual warranty and support on the PM951, the 256GB drive would be a decent pick as our budget NVMe SSD, but if you buy one, you're basically on your own. That means no firmware updates are likely to appear during the life of the drive, and the drives aren't even recognized by the current version of Samsung's SSD Magician software. That's just too many tick marks in the negative column for us to consider recommending these OEM models. On the other hand, if Samsung were to offer a retail variant (950 Evo, anyone?), we would be interested.
An Eye Toward the Future
That takes care of the recommendations for existing NVMe SSDs, but as we mentioned above, there are many products slated to ship in the coming months. We previewed most of these at CES 2016, and with more consumer NVMe drives coming out, we're hoping to see more competition on pricing. 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, of course, 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, naturally, so until more systems use NVMe SSDs, prices will stay higher. And we're still waiting with baited breath for more details on 3D XPoint Technology, but let's get to the drives we know about.
First up, Patriot announced their Hellfire SSDs, scheduled to ship in the March time frame. These will use the new Phison 5007 controller, and while traditionally Phison hasn't offered top performance, they've improved over the years, so it will be interesting to test the Hellfire. The Hellfire will come in two forms, M.2 and add-in card (AIC), with capacities of 240GB/480GB/960GB. It will use MLC NAND, with performance rated at up to 3,000/2,200 MB/s read/write. Whether it can sustain those values remains to be seen. Zotac has a similar-looking AIC NVMe drive coming, also using the Phison 5007 controller, with speeds rated at up to 2,500/1,200 MB/s, and it should be available later this month or early next. Planned capacities and pricing were not revealed.
OCZ has been a long-time player in the PCIe AIC SSD market, going back to their original RevoDrive in 2010. At CES, they announced their new RevoDrive 400, an M.2 solution with capacities up to 1TB. OCZ didn't provide any details on the controller or pricing, but did state that the RevoDrive 400 will offer read/write speeds up to 2,400/1,600 MB/s. Given those specs, it's entirely possible the RevoDrive 400 will use the same Phison 5007 controller as the Patriot and Zotac drive—not to mention OCZ/Toshiba have used Phison controllers in several other drives of late.
Next, Kingston has an NVMe version of their HyperX Predator slated to launch this year. The non-NVMe Predator didn't set our pants on fire, but the new drive was posting read/write speeds of 2,585/1,354MB/s at the Kingston CES booth. The company hasn't provide too many details yet, other than planned capacities of 240/480/960GB. Like the current Predator, it will be an M.2 form factor drive, though a PCIe AIC adapter will also be available. Unfortunately, there was no word on pricing, launch date, IOPS performance, or controller provided. Even less is known about Plextor's M8Pe, other than that it will be offered in an AIC format and features a PCIe x4 Gen3 interface. It's rated at up to 270K/150K read/write IOPS, which is similar to Samsung's 950 Pro, but we'll have to wait for more details.
The good news is that with no fewer than five new consumer NVMe SSDs set to launch in the coming months, competition in this market is about to become a lot more interesting. 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.
