The Best Internal SSDs for 2021

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 or USB 3.2 Gen 2×2 is in the range of 2,500 megabytes per second (MBps) for reads and 2,000MBps for writes.

ADATA Spectrix SSDour 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, especially if it’s a game or backup drive. At capacities of 4TB or above, 2.5-inch SATA drives are often much cheaper than their M.2 counterparts. Take the new SATA-based Samsung SSD 870 EVO, for example, which retails for $479 for the 4TB version, while the M.2 Sabrent Rocket Q 4TB goes for a whopping $829.99. In these scenarios, choosing a SATA-based option that still keeps up in 4K random read and writes is the value move, and will give you more budget to play with when upgrading the rest of your system.

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.

Kingston 2.5-Inch SSDM.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.

WD Blue SN550 M.2 SSDrumored to be on the way), 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 in straight-up sequential runs, 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.)

ADATA SU750 2.5-Inch SSDMushkin 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 (example: the Sabrent Rocket Q model mentioned earlier).

Mushkin Source176-layer, with the last still being just an announcement, with no drives in circulation that put it to the test just yet. 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.

Crucial M.2 SSDSamsung SSD 870 EVO, which topped out at 3,372MBps read speed in the Crystal DiskMark 6 benchmark.

Finally, as mentioned earlier, there’s PCIe 4.0, which currently 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 or MSI’s upcoming PCIe 4.0 SSD.

The SSD 980 Pro comes in just shy of hitting its promised marks in our Crystal DiskMark 6.0 sequential throughput testing.

Third-party reviews like PCMag’s, not vendor numbers, are the only true measures of SSD speed, though. In our testing of PCIe 4.0 drives (specifically via a deep-dive through the data of PCMark 10), we found the sky-high sequential numbers advertised by PCIe 4.0 drive manufacturers often don’t mean much for how a drive will perform when tasked with handling real-world scenarios like booting into Windows 10, launching games like Overwatch, or booting into programs like Adobe Photoshop and Adobe Premiere.

Check out some of our PCMark 10 results below to get an idea of what we’re talking about…

In those tests, drives from every connection interface to bus type from PCIe 4.0 down to SATA III can trade blows, and the best among them, like the SATA-based Samsung SSD 870 EVO (4TB and 1TB), can take top marks away from drives that are a good deal more expensive per gigabyte.

If you’re trying to get the most gaming, application, or operating system performance for the lowest cost per gig, there are still SATA-based options out there that will either match or beat the proposition of M.2 competitors where it counts.

That said, if you have an M.2 slot and are shopping in capacities of 2TB or below, the price per gig starts to even out between most SATA options and M.2. The drives are still faster in sequential by a lot, which is important for moving stuff around (backing up your PC each day, for example), and if you can find one that matches the price of a competing SATA option, the M.2 should take the front of the line. Often, though, especially with updating a laptop, you’ll only have one choice of interfaces.


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.

Samsung SSD 870 QVOwe’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.

About Chris Stobing

February 6, 2021
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