Solid-state drives (SSDs) have come a long way in recent years: a long way up in speed and capacity, and a long way down in price.
Technology that was previously reserved for enterprise customers and the PC performance elite has gained the common touch, with mainstream desktops and laptops now featuring SSDs rather than hard drives as primary storage choices. And adding an internal SSD to an older PC as a new boot drive remains a great, cost-effective upgrade. If you’re still relying on spinning metal, you’ll find it one of the easiest ways to an instant, undeniable speed boost.
That said, while almost any SSD is much faster than any hard drive, not all SSDs are created equal—not by a long shot. SSD interfaces have evolved greatly of late, and SSDs themselves are taking on different shapes and core technologies.
This guide will help you sort through the different confusing terminologies associated with SSDs, as well as learn what you need to know when it comes to pricing, speeds, durability, warranty durations, and more.
Are You Upgrading a Laptop or a Desktop?
First, some context on the difference between internal and external SSDs. Most of what you need to know is obvious from the name. “Internal” means the drive goes inside a desktop PC or laptop, while “external” means it connects to a computer via a cable. But it’s good to know some nuances regarding how fast each kind can be.
External SSDs are drives with their own standalone enclosures, which plug into your laptop or desktop via a USB cable or (less commonly) a Thunderbolt 3 cable. Most are built for portability, with some small enough to fit on a keychain. On average (because of the limitations of current bus technology), the higher end of the sequential speed spectrum you should expect to see over Thunderbolt 3.0 is in the range of 2,500 megabytes per second (MBps) for reads and 2,000MBps for writes. For USB, real-world bandwidth will top out around 1,000MBps even with USB 3.1 Gen 2.
Internal SSDs are more complicated. You’ll see them in three main physical forms: (1) 2.5-inch drives, (2) M.2 drives, and (3) add-in-board (AIB) SSDs. Within those three physical forms are some crucial variations, though. M.2 drives and AIB SSDs transfer data between the drive and computer via one of two bus types: the same Serial ATA bus used by 2.5-inch drives, or the PCI Express bus, the lanes and pathways of which can also be used by other hardware, such as graphics cards. (If you’d like a deep overview of all the SSD terms shoppers should know, check out our SSD dejargonizer for a full breakdown.)
When buying an internal SSD to upgrade or augment a system you own, start by figuring out what your system can actually accept: a 2.5-inch SATA drive only? Does it have an M.2 slot? What length of M.2 drive can it take, and using which bus type? If you’re upgrading a laptop, in most cases you’ll have the option only to swap out the internal drive, not to add another. If you can’t get the info off the web beforehand, or from the manufacturer, you’ll need (in most cases) to open up your laptop to see whether you have upgradable storage in the first place. (That is, if you can open it at all.) With laptop upgrades, you typically have much less flexibility than upgrading a desktop; your only option might be buying a drive in a higher capacity than the existing one, since you’ll likely have only one M.2 slot or 2.5-inch bay to work with. (See our favorite SSDs for laptop upgrades.)
For a desktop, the right SSD to buy depends much more on what you are doing and what your aim is. If you’re building a new PC from scratch, you definitely want an internal M.2 or 2.5-inch SATA SSD as your boot drive nowadays. A 2.5-inch SATA drive might only make sense if you’re upgrading or building from older hardware; almost all new motherboards now have at least one M.2 slot of some kind, and these drives save lots of space in compact PC builds. If you’re installing an SSD as a secondary drive, you can probably choose between 2.5-inch or M.2. And if you’re simply replacing a hard drive as your boot drive, you’ll love the speed boost. We guarantee it.
What Form Factor of SSD Do You Need?
We’ve introduced you to M.2 drives and 2.5-inch drives above, but let’s get into them in a bit more detail.
2.5-Inch SSDs: The Basic Drive
The 2.5-inch Serial ATA SSD is the most common type of internal solid-state drive you’ll encounter. It was one of the earliest consumer-facing implementations of SSD technology and remains wildly popular, especially for upgrading older PCs. While the drive electronics are much smaller than 2.5 inches, its enclosure will measure a bit wider (actually 2.75 inches wide, despite the name), so it will fit into the same mounting brackets in your desktop or laptop used by 2.5-inch hard drives. That makes them your most likely choice for upgrading a platter-based boot drive in an older laptop. And almost any desktop PC nowadays will have 2.5-inch bays, or let you boot a 2.5-inch drive in a 3.5-inch hard drive bay.
If you’re upgrading an older laptop, you’ll also want to account for the thickness of a 2.5-inch SSD. Almost all SSDs nowadays conform to a 7mm thickness, but older laptops with SATA hard drives may have drive bays with as much as 9.5mm clearance. Some SSD makers bundle a space-filling frame with their drives to keep a thinner 7mm drive from rattling around in a roomier bay. That’s less common today than in years past, though.
M.2 Drives: Stick-of-Gum Speedsters
M.2 slots are increasingly common in new desktop motherboards and practically universal in late-model laptops. M.2 solid-state drives are the 2.5-inch drive distilled to its essence, extremely minimal in their design and implementation. They’re also the most complicated to understand before you buy.
First, consider the bus type. M.2 drives come in SATA bus and PCI Express bus flavors, and the drive requires a compatible slot to work. Some M.2 slots support both buses on a single slot, but no drives can support more than one, so make sure the SSD you buy matches the bus type available on the slot in question.
M.2 drives also come in different lengths. Physically, the most common of five M.2 SSD sizes is what’s known as Type-2280, shorthand for 22 millimeters wide and 80mm long. (All SSDs you’ll see for consumer PC upgrades are 22mm wide; lengths range from 30mm to 110mm.) Most are merely circuit boards with flash memory and controller chips on them, but some M.2 drives (especially those of the PCI Express 4.0 variety) now ship with relatively large heatsinks mounted on top to keep them cool.
If an M.2 drive you’re looking at has one of these special, big heatsinks on it, make sure your desktop’s motherboard has the clearance above and around it to accommodate its bulk. Some desktop motherboards situate an M.2 slot right alongside the ideal expansion slot you’d use for your graphics card, for example, and the hardware can collide. Laptop designs typically can’t stomach a special, tall heat sink at all.
What Bus Type of SSD Should You Buy?
Let’s get into the issue of bus type in a little more depth. Oftentimes, you won’t have a choice of what bus variety you need. But you need to know some background to figure out what you have and what you should buy.
SATA: The Old Standard
Serial ATA is both a bus type and a physical interface. SATA was the first interface that consumer SSDs used to connect to motherboards, like the hard drives that preceded them. It’s still the primary cable-based interface you’ll see for 2.5-inch solid-state drives.
The SATA interface is capable of sequentially reading and writing a theoretical maximum of 600MBps in an ideal scenario, minus a bit for overhead processes. Most of our testing has shown that the average drive tops out at roughly 500MBps to 550MBps; the real-world difference between the best SATA drive and a merely average one is pretty small.
PCI Express: Where Speed Is Going
The original implementation of the PCI Express interface for SSDs took the form of cards that occupied one of the PCIe slots on a desktop motherboard, and you can still find carrier cards that let you plug M.2 drives into a standard PCIe slot. Nowadays, though, the most popular PCI Express SSDs mount into an M.2 slot, though as we said above, you should make sure that your M.2 slot (assuming you have one in the first place) supports PCIe drives before you make your purchase. Some support only the SATA bus; some support PCIe only; and some support both.
A further wrinkle around the PCIe bus: Some drives and some slots support a newer transfer protocol known as NVMe (for Non-Volatile Memory Express). NVMe is a standard designed with flash storage in mind (opposed to the older AHCI, which was created for platter-based hard drives). In short, if you want the fastest consumer-ready SSD, get one with NVMe in the name. You’ll also want to be sure both drive and slot support NVMe. Some early M.2 PCIe implementations supported PCIe but not NVMe.
PCIe 3.0 NVMe SSDs have been the standard for a number of years, but now with the launch of the third-generation Ryzen processors from AMD in 2019, PCIe 4.0 is setting new peak-speed records for consumer storage. On the market, you will find three iterations of PCI Express drives in production right now: PCIe 3.0 x2, PCIe 3.0 x4, and PCIe 4.0 x16 (the “x” in each of these naming schemes refers to how many lanes the drive has available to transfer data). A mainstream choice is a PCIe 3.0 x4 drive; you’ll only want to consider a 4.0 model if you have a very new AMD Ryzen-based desktop based on the X570. B550, or TRX40 chipsets. (Check the specs for PCI Express 4.0 support, and on which slots, before you dive in.)
Even PCIe 3.0 is significantly faster than SATA, though, and the interface is set to get even faster over the coming years as PCIe 4.0 makes its way into the mainstream.
What Capacity Do You Need, and What’s the Cost per Gigabyte?
Okay, you’ve figured out the bus type, interface, and form factor of the drive you need. The next factor to look at in determining your next SSD purchase is the capacity of the drive. A lightly used Windows or macOS machine shouldn’t need a drive larger than 250GB or 500GB as the main boot drive, but gamers and content creators will need to get at least 1TB in order to store sufficient games and 4K video comfortably on their drives. On a desktop, they may also want to consider offloading their game library or video scratch disks onto cheaper, roomier hard drives.
That said, with games like Call of Duty: Modern Warfare requiring over 100GB of space just for one title, the drive could end up full again faster than you can line up a sniper shot. These days, if you’re looking to get just one drive (or maybe you have to, such as in a laptop), 2TB is the recommended size for gamers, while hardcore content creators who are dealing with 8K RAW footage will need far, far more. (A one-hour 8K RAW file will occupy 7.92 terabytes of space.)
But big drives don’t come cheap (especially when you’re talking about SSDs rather than hard drives), so knowing the value of an SSD and how much it costs per gigabyte is another important factor to weigh in your next upgrade. Whether it’s 128GB or 4TB (or any capacity, really), the cost per gigabyte will give you a baseline to compare one drive against another and whether or not it looks like a good value based on its features and durability rating.
On average, an internal SSD can cost anything from 9 or 10 cents per gigabyte (example: the 2.5-inch SATA-based Mushkin Source, with 1TB for just a bit more than $90) to 62 cents per gigabyte for the pricey, specifically-for-filmmakers Sony SV-GS48. A general rule is that smaller drives (anything under 240GB) will cost more per gigabyte, getting cheaper as you go up to the 500GB, 1TB, and 2TB capacity tiers. Sometimes, though, a 2TB or 4TB drive will demand a price premium per gigabyte over the smaller-capacity models in a line.
The number of “layers” in an SSD has been a driving force in bringing costs down in recent years. SSDs (and the NAND flash memory modules they’re made from) have seen a lot of innovation over the past half-decade, and one of those technologies is known as 3D NAND. The term refers to a fabrication process in which storage cells, rather than being laid exclusively on a horizontal plane, can be stacked atop one another in layers. The more layers, the more storage capacity fits in a smaller space, and thus the lower the material cost.
Right now, the three main processes in 3D NAND are 32-layer, 64-layer, and 96-layer, with the last only hitting the mainstream over the past year or so. More layers don’t necessarily bring a performance bonus, but generally bring a lower price for drives of the same capacity.
Finally, the price of an SSD can also be affected by the memory element “method” used to store data. The four different types are single-level cell (SLC), multi-level cell (MLC), triple-level cell (TLC), and quad-level cell (QLC), respectively storing one to four bits per cell. SLC is both the fastest and most durable of the four types, but it’s also the most expensive and rarely seen outside enterprise environs. MLC is less durable and a bit slower, but more reasonably priced, while TLC and QLC have pretty much taken over the mainstream; they are the least “durable” but also the cheapest. (More on drive endurance in a moment.)
How Fast Is the SSD I’m Looking at?
When an SSD manufacturer advertises the speed of a particular drive, it will usually be shown in one of two ways: the maximum theoretical sequential read/write speeds (expressed in megabytes per second), or the maximum theoretical random—or “4K,” as in four-kilobyte blocks—read/write speeds (expressed in IOPS or input/output operations per second). In practical terms, however, 4K read/write results can be expressed just as easily in MBps.
Sequential write speeds are generally (though not always) tied to the results you can expect while transferring large singular files (think of a high-resolution movie or ISO optical disc image), while 4K read/write results are more reflective of things like game loading times or how quickly your operating system can fetch files.
The max sequential read speed that’s theoretically possible for a SATA drive is 600MBps, though as we said above we haven’t seen any drives reach that limit even in ideal testing conditions. The theoretical max sequential read speed for PCIe 3.0 x4 drives is much faster—3,940MBps, although the fastest one we’ve tested in-house at this writing is the Samsung SSD 970 EVO, which topped out at 3,372MBps in the Crystal DiskMark 6 benchmark.
Finally, as mentioned earlier, there’s PCIe 4.0, which currently exists in only a handful of drives and requires (at the moment) an X570- or B550-chipset AMD Ryzen desktop motherboard (or a TRX40-based Ryzen Threadripper one). PCIe 4.0 x16 solid-state drives have a theoretical max sequential read speed of 31,500MBps, though the only people who might actually notice (or even be able to hit) that kind of sky-high throughput on a sustained basis are those transferring enormous files between two PCIe 4.0 M.2 drives installed on the same motherboard. (Otherwise, the source or destination drive will be a bottleneck.) In reality, 7,000MBps is the realistic ceiling, and that only in the latest-model drives like the Samsung SSD 980 Pro.
Third-party reviews like PCMag’s, not vendor numbers, are the only true measures of SSD speed, and even then, they are mostly useful for PCIe and NVMe drives—most SATA drives are imperceptibly different in speed.
What’s the SSD’s Warranty and Endurance Rating?
An SSD metric called terabytes written (TBW) refers to the point where, after a certain amount of data being written to the drive, its cells will begin to fail, meaning the available space on the drive will shrink as the drive electronics compensate and decommission the failing cells. The TBW rating of a drive is usually anywhere between 100TBW and 3,500TBW, depending on the manufacturer, the capacity, and the use case, but for the most part this isn’t a figure that will affect daily users.
That said, those buying an SSD for professional applications such as filmmaking, server hosting, or anything else that involves large file transfers of the magnitude of hundreds of gigabytes daily will want to choose a drive that can withstand that kind of punishment for months, even years on end.
This figure also folds into the warranty period for a drive, which (aside from a few fringe cases) will almost always be for three to five years or until you hit the TBW spec. Manufacturers have ways of reading a drive to determine how many terabytes have been written to it over its lifetime, so make sure before you submit any warranty requests that you haven’t already gone over your TBW before the warranty period has expired.
Is the Software and the Controller Type Important?
Controllers are a factor of SSD buying that only ultra-geeks will care about, but they’re still important. The controller is a module on the SSD that essentially acts as the processor and traffic cop for the drive, translating the firmware instructions into features like error code correction (ECC) and SMART diagnostic tools, as well as modulating how well the SSD performs in general.
It’s possible to detect some commonality among drives using similar controllers (such as the Phison controllers used by many drive OEMs). Some SSD makers use third-party controllers, while others manufacture their own. You may see the controller model mentioned on drive spec sheets or in reviews, but know that for casual buyers, it’s totally inside baseball.
Software is another shopping consideration that only the storage nerds out there might dig into, but regardless of which company you go with, any SSD software management dashboard should have at least a secure erase option, a firmware update module, and some kind of migration tool that will let you safely and securely move data from one drive to another. Most mainstream drives will have you covered there.
Internal SSD Outliers: U.2, mSATA, HHHL
If you’ve read through this whole buying guide and have a particular port or slot not covered yet, that’s because you probably have one of the two outlier ports installed in your system: U.2 or mSATA.
U.2 is pretty rare in consumer PCs; it’s mostly made with enterprise customers in mind. A U.2 drive like the Intel SSD 750 Series connects to a U.2 port on the motherboard via a special cable, or to a PCI Express M.2 slot using a special adapter. These drives almost always come in the 2.5-inch form factor. Unless you have a U.2 port on your desktop motherboard you want to use, you can ignore them.
mSATA, short for mini-SATA, is the original predecessor to the M.2 form factor. It was primarily built into laptops, though some older desktop motherboards may have an mSATA slot aboard. With mSATA, the slots and drives use only the SATA bus, unlike M.2’s SATA and PCIe support. For all intents and purposes, mSATA is a dead end, though you might run into it if you have an older laptop or desktop.
Last of all is the SSD on a PCI Express expansion card, much like a small graphics card. Most use the HHHL (half-height, half-length) form factor, letting them fit into compact, low-slung PCs, and plug into the same PCIe ports you’d plug any other expansion card. You’d only want to opt for one of these, though, on a desktop PC that lacks an M.2 slot or a SATA port/drive bay you can use.
So, Which Internal SSD Should I Buy?
Solid-state drives come in all shapes and sizes and are built for almost every purpose. Whether you need a drive that can survive a trek through the desert or one that will load up a 4K movie in less than half a second, there’s an SSD made for the job.
Before we jump into the list of the best drives we’ve tested recently, we should mention that although this is a roundup of the best internal SSDs, these days just about any such drive can be turned into an external USB unit with the help of an SSD enclosure. These are often little more than durable housings of plastic or metal, and you can buy enclosures for almost any type of SSD: SATA 2.5-inch, SATA M.2, or PCIe M.2. Just make sure that the enclosure supports the form factor and bus type of the drive you want to “externalize.” Of course, you can also buy premade external SSDs; we’ve rounded up the best of them, as well.
With that, let’s get to our picks. Our choices span across 2.5-inch SATA drives, and M.2 drives of both bus types.
