Summary

• The endurance rating (TBW) of an SSD determines its lifespan; most SSDs with regular use can last for well over 5–6 years.
• The type of NAND flash (SLC, MLC, TLC, QLC) determines the cost, performance, and durability of your SSD.
• Having a high-end controller can improve performance manifold; DRAM can boost sustained write operations.
• The random read/write speeds of an SSD are more indicative of real-world performance in gaming and general desktop use.

The world has, more or less, moved on from hard drives. Everyone knows that an SSD is much faster than an HDD, and an NVMe SSD is faster than a SATA SSD. When buying a new SSD, most users are aware they need to look at the more obvious specifications such as the interface (SATA/NVMe), PCIe generation (Gen3, Gen4, Gen5), capacity, and the advertised read/write speeds.

However, there's a set of not-so-readily apparent specs that some users might overlook. These specs pertain to the quality of the components used inside the SSD, and determine most of the SSD's real-world performance. If you're about to buy a new SSD, pay attention to these specs in addition to the ones listed above.

5 Endurance

Longevity is just as important as speed

You don't want a high-speed SSD that'll die on you in a year or so, do you? SSDs have a limited lifespan, just like any other electronic equipment, so it's important to know an SSD's endurance rating before buying it. Although most SSDs from reliable brands have minimal chances of early failure, you should still cross this specification off your checklist when you're shortlisting SSDs.

Even with an unrealistic amount of data (for most users) written to an SSD every day, 600TBW will last you for 5 to 6 years.

Endurance is typically measured in Terabytes written (TBW), which means the amount of data in TB that can be written to the SSD in its lifetime. Most 1TB SSDs on the market come with a 600TBW rating, so you can write 600TB of data (cumulatively) on the drive before it shows signs of failure. Even with an unrealistic amount of data (for most users) written to an SSD every day, 600TBW will last you for 5 to 6 years.

4 Type of NAND flash

SLC, MLC, TLC or QLC?

Every SSD is composed of NAND flash memory that stores all your data. Now, NAND flash can be of different types, depending on the number of bits that can be stored per cell. Single-level cell (SLC) NAND can store one bit per cell, and is therefore, the costliest but also fastest and most durable. Similarly, multi-level cell (MLC), triple-level cell (TLC), and quad-level cell (QLC) NAND can store two, three, and four bits per cell respectively.

SLC drives are suitable for servers and setups where longevity is paramount, whereas MLC and TLC are used in consumer drives, offering a good combination of cost and performance.

As you stack more bits per cell, the cost goes down as you can manufacture SSDs with more capacity in the same space. However, the speed and durability go down as well, so it's a trade-off. SLC drives are suitable for servers and setups where longevity is paramount, whereas MLC and TLC are used in consumer drives, offering a good combination of cost and performance. QLC drives are best for high-capacity drives where speed is secondary.

If you're buying an SSD as a boot drive or to store your games, make sure you try to get one with TLC NAND, which is the one used in most high-performance consumer SSDs.

3 Controller

The one to control them all

Every SSD has an onboard chip that's responsible for executing all the operations of the drive and communicating with the system. This chip determines a lot of the drive's performance, efficiency, and reliability, so try to check what controller is inside the SSD you're buying (if possible). Most consumer SSDs feature controllers made by Phison, SMI, Marvell, Realtek, Samsung, or Intel.

The better the controller, the faster the data transfer, the lower the latency, and the higher the input/output operations per second (IOPS).

Brands like Samsung and Intel manufacture their own controllers for their SSDs, whereas others use the ones made by Phison, SMI, Marvell, and others. The better the controller, the faster the data transfer, the lower the latency, and the higher the input/output operations per second (IOPS). Of course, a controller alone isn't the complete picture, but whenever possible, check if your SSD has a good controller inside it.

You can refer to third-party reviews to check the performance of the controller in particular and the SSD in general. It's not always mandatory to know the controller in the SSD you're buying, as the benefits of a quality controller will be readily apparent in other performance areas in whichever review you decide to refer to. Still, just like endurance, it's something you should have on your checklist.

2 DRAM or DRAM-less

What do you use your SSD for?

DRAM is a high-speed memory buffer that stores frequently accessed information to speed up certain operations on your computer. If you only care about gaming on your PC, having a DRAM cache on your SSD might not make any tangible difference, as gaming is a read-heavy workload. However, for those who transfer a lot of large files to the SSD regularly, DRAM can speed up the process significantly.

Although DRAM-less drives have gotten better at using system resources to substitute for DRAM, you should go for a DRAM drive if the cost difference isn't significant.

These types of workloads where sustained read/write speeds come into play benefit the most from DRAM. These are the same speeds that are advertised on SSDs, hence the benefits of blazing-fast PCIe 5.0 SSDs for professionals and creators. Although DRAM-less drives have gotten better at using system resources to substitute for DRAM (specifically HMB), you should go for a DRAM drive if the cost difference isn't significant.

1 Random read/write speeds

How many IOPS is your SSD capable of?

Instead of being razor-focused on the sequential (advertised) speeds of an SSD, you should also look at the random read/write speeds. Instead of the 10,000MB/s+ sequential speeds we see on the PCIe 5.0 drives, random read/write speeds are more indicative of most real-world use cases like gaming and general desktop usage. It's not always easy to find the random read/write speeds on the SSD product page.

Measured in IOPS, high-end SSDs like the 990 Pro can reach 1.6 million IOPS/1.5 million IOPS of random read/write speeds.

You can find it more easily in third-party reviews. Measured in IOPS, high-end SSDs like the 990 Pro can reach 1.6 million IOPS/1.5 million IOPS of random read/write speeds. Other SSDs like the WD Black SN770 can reach 800,000 IOPS for both read and write operations. If you're not a prosumer who's going to make full use of the sequential speeds, pay close attention to the random read/write speeds of the SSD you're planning to buy.

Know your SSD

Buying a decent SSD has become easier than ever — just get a Gen4 SSD within your budget, a Gen3 model if you have an older motherboard, or a Gen5 one if you need the extra speed for your workloads. For recommendations on specific models in each of the categories, you can refer to resources like our best SSDs list. Most popular models from reliable brands will not disappoint a regular user, unless the manufacturer has engaged in some serious cost-cutting.

However, during the process, you should also try to stay informed of the detailed specs of the SSDs you're considering. And besides the big ones such as sequential speeds, capacity, and interface, ensure that you're finding out about the controller used in the SSD, whether it has DRAM or not, or the random read/write speeds it is capable of. This will help you land on the best SSD you can buy within your budget.