Solid-state drives that adhere to the NVMe protocol are the fastest internal storage drives you can buy for building a PC or upgrading certain laptops. Here’s how to choose one with confidence, along with the top NVMe SSD picks from our deep-dive reviews.
Shopping for an SSD means facing a sea of acronyms. The trickiest of them are jagged reefs sticking out of the water, shaped like circuit boards and ready to run your upgrade aground if you’re not careful. We’ve already mentioned one you know—SSD. It stands for «solid-state drive,» a storage drive made up of flash memory in modules called NANDs and governed by a controller chip. (The name NAND comes from a type of logic gate in Boolean algebra; we’ll try to explain terms as we go along, but if you need a refresher in SSD lingo see our rundown of 20 terms you need to know.) Unfortunately, SSD shopping has been complicated in recent years by the emergence of three new technologies: M.2, PCI Express (abbreviated PCIe), and NVMe. All three are centered around making SSDs smaller or faster. They also make buying a solid-state drive more challenging than ever. SSDs: Why They Are Changing Shapes Until the last few years, the typical SSD was a little slab, designed to fit into the same space or drive bay inside a PC as a spinning hard drive. You can still find SSDs in this form factor, known as 2.5-inch drives, but times have changed. Almost all new desktop motherboards and the logic boards of most current laptops incorporate slots meant for much smaller SSDs. These are known as M.2 slots, and they accept SSDs that look like sticks of silicon chewing gum. And depending on the drive, that slim little stick may deliver much faster storage than the bigger drives you’re used to. (Photo: Zlata Ivleva) Why did SSDs take so long to get so small? Actually, from a strict manufacturing viewpoint, they never needed to be that big in the first place. Classic 2.5-inch SSDs have a lot of dead space inside, as memory chips are much smaller than rotating drive mechanisms, but they were designed to fit into existing bays to replace hard drives. In the move from bulky desktops to ultra-slim laptops and tablets, one thing came clear: That fatter kind of drive would have to go. An M.2 drive reduces an SSD to its essentials: just a strip of a circuit board studded with silicon, much leaner and easier to fit into tight spaces. First, a Bit About M.2 Most M.2 drives aren’t exactly pretty; they look like bare circuit boards with silicon chips grafted onto them. Some may be topped by a heat spreader or heatsink (usually an array of metal fins) that is equal parts practical and decorative. The most important thing to know about M.2, though, is what it is and what it isn’t. (Photo: Zlata Ivleva) Although M.2 is commonly referred to as an interface, that’s not the whole story. M.2 is also a shape or physical form factor, and governs the keying that lets a drive fit onto a motherboard. The data bus, or pathway, over which your data travels to and from an M.2 drive is a whole other matter, which is where PCI Express and NVMe come in. We’ll get to the significance of NVMe in a moment; first, let’s discuss the key physical traits of an M.2 drive that you need to understand. (The video below is a good primer.) As we discuss in our parallel roundup, The Best M.2 Solid-State Drives, M.2 drives are differentiated by a four- or five-digit number listed in their names or specifications. The number is a measurement in millimeters, with the first two digits being the drive’s width and the remaining two or three digits telling you how long it is. In practice, all of today’s PC builder- or upgrader-minded M.2 drives and slots are 22mm wide, so you can expect this number to start with 22. The most common lengths are 80mm (M.2 Type-2280) and 60mm (M.2 Type-2260). Drives as short as 30mm (M.2 Type-2230) or as long as 110mm (M.2 Type-22110) do exist, however. Why the differences in length? The longer the drive’s PCB (printed circuit board), the more surface area it has to hold memory chips. Length mostly matters when fitting an M.2 drive into a laptop. Most desktop motherboards with M.2 slots have mounting points for different drive lengths, whereas most laptops fit just one size. Check the space available before you shop. M.2 drives in Type-2242, Type-2260, and Type-2280 sizes An M.2 drive’s length doesn’t always correlate 1:1 with its capacity, but the bigger the stick, the more memory modules engineers can fit onto it. Due to space and density limits, most M.2 drive families top out at 2TB, though 4TB and even 8TB M.2 SSDs exist. You’ll see five broad classes of capacity as you shop, with minor variations according to how much data the drive maker has put aside for overprovisioning (a safety margin for when the drive ages and cells start to fail). These capacity classes are: 120GB or 128GB 240GB,250GB, or 256GB 480GB,500GB, or 512GB 960GB or 1TB 2TB Now let’s reiterate an important point: You may know an M.2 solid-state drive’s length and capacity, but that doesn’t tell you about the bus or interface it makes use of. That detail is vital to know—just as important as making sure the drive physically fits in the space you have.
