Shopping for storage can be a strange endeavor. In many cases, items with the same capacity and the same connector (with the same theoretical speed limitations) can cost wildly different prices. Demystifying this can be a process in itself, and comparing SSD features while shopping for one can be just as difficult.

We'll take a look at some of the things that differentiate SSDs, and what you should look for when upgrading the main drive in your PC. Let's examine the differences between drives with the same top-line specs, to find out what it is that actually sets drives apart which have the same capacity and connector/interface.

The brain of an SSD is its controller

Controller technology can have a big impact on SSD price (and speed)

One of the biggest factors that impacts an SSD's overall speed (and potentially lifespan) is its controller. The controller is the brain of an SSD, and handles many of the onboard processes managed by the SSD, as opposed to your operating system. When an SSD is connected to your computer, it presents a unified API, which is a standardized interface available to your operating system to interact with it. This is what's used to manage your data, make changes on the disk, or request information, but this doesn't handle processes inherent to the SSD like garbage collection, wear leveling, and error correction.

Some of these functions are more important than others. A high quality controller will have all of the above. Effective wear-leveling can prolong your SSD's lifespan considerably. A good controller can make all the difference between an SSD that stays fast and performs well for a decade or more, and one that dies after a few years. Most controllers from reputable brands are high quality and support all the features you're likely to be worried about. This is something to seriously consider when buying a budget SSD from a lesser known brand though, because the quality of the controller may vary greatly.

Drives have their own DRAM cache

DRAM cache is essential for speed and throughput

Another factor that can have an impact on SSD pricing is the quality and quantity of the DRAM cache on the SSD itself. This DRAM cache works analogously to the L3 cache on your CPU, offering a small but high-speed buffer which can be used for a variety of functions, like fast access to your SSD's mapping table or a temporary buffer for data writes. It keeps things easily accessible to support quicker speeds. The existence of a cache can significantly impact your drive's performance, and a larger cache can help with overall throughput (especially if you've got multiple applications or processes accessing data simultaneously).

Some budget SSDs will skip a cache entirely, while a larger and faster cache is a key feature of more expensive enterprise SSDs. The size of a drive's cache and its technology isn't often advertised on product pages for consumer sites, but more in-depth review sites like Tom's Hardware will often explore what cache size is available for a drive. For example, Tom's Hardware's review of the oft-recommended Samsung 990 Pro includes information about the 2GB of LPDDR4 cache available, as well as the onboard controller.

The manufacturer's product pages will also often have more in-depth specs available, like Samsung's product page for the 990 Pro, but these often need an experienced technical eye to understand. Adding DRAM to an SSD obviously impacts its price, and again, budget SSDs with no DRAM typically have significantly lower performance, especially with heavy concurrent workloads over time.

Type of NAND flash used

The differences in NAND flash can be difficult to decipher, but have a big impact

One almost-invisible difference between SSDs at different price brackets is the quality difference in the NAND flash used. This can often be difficult to get information about, but the overall quality and endurance ratings of more expensive flash can give your drive better overall performance for longer. The lifetime capacity of NAND flash is usually expressed in TBW (terabytes written). Some manufacturers might publish ratings and warranties for their flash, guaranteeing a certain number of writes to the flash before it ultimately dies, but this isn't common (especially for more budget-oriented drives.) This is another area where brand recognition and reputation come in, with some of the more expensive reputable manufacturers publishing data on and consistent use of high-quality flash. This gives these quality drives a lower failure rate and longer endurance.

Using the Samsung 990 Pro as an example again here for reference, Samsung publishes a TBW of 600TB over the drive's lifetime.

There are some other considerations when comparing NAND flash, some of which are more relevant than others. The differences between single and multi-layer SSDs are something we've covered over on HowToGeek. Most consumer SSDs are using TLC NAND flash (triple level cell) in 2024, so we wouldn't worry about this as a factor if you're buying from a reputable brand. Some white-label extreme budget SSDs might be using QLC (Quad-Level Cells), which we'd recommend avoiding due to the performance tradeoffs that come with them.

As with most things, you get what you pay for in an SSD

As we've highlighted, there are some significant differences between seemingly identical SSDs that can impact performance. These can be hard to compare, especially as information on the specs of budget-friendly drives can be hard to find. We'd recommend staying with reputable brands such as Samsung, Crucial, and Western Digital for your main drives. If you are looking for a great quality budget SSD, these do exist! But be sure to do your research on the quality of the controller used, the available DRAM cache on the drive, and potentially the type of NAND flash used. All of these things can affect both out of the box performance and the drive's longevity in the long term.

If you're looking for an easy way to compare SSDs from similar reputable brands, comparing random read/write speeds (or IOPS) can be a great way to do it - but be careful, because that often doesn't reveal the whole story.