Storage Drive Glossary

An SSD stores data on flash memory chips rather than spinning disks. The result is near-instant load times, silent operation, and no moving parts to break. SSDs are now the standard choice for laptops and desktops alike.

NVMe is the fastest type of SSD available for consumers. It connects directly to the CPU via PCIe lanes rather than going through a slower storage controller. If you want the best performance for gaming, video editing, or heavy workloads, NVMe is the way to go.

The interface is the physical connection between the drive and your computer. NVMe is the fastest, connecting directly to the CPU over PCIe. SATA is the older, slower standard used by 2.5″ SSDs, still found in older systems and budget builds.

PCIe is the high-speed connection that links your SSD directly to the CPU. Each new generation roughly doubles the bandwidth of the previous one. Gen 3 is fast enough for most users, Gen 4 is mainstream for gaming and creative work, and Gen 5 sits at the cutting edge of consumer storage.

Each PCIe generation doubles the data bandwidth available to the drive:

• Gen 3: up to ~3,500 MB/s read. Reliable and affordable.
• Gen 4: up to ~7,000 MB/s read. The sweet spot today.
• Gen 5: up to ~14,000 MB/s read. Cutting-edge, runs hot, and carries a price premium.

Your motherboard and CPU must support the generation you want to take full advantage of it.

SATA is the older interface standard, used by 2.5″ SSDs and traditional HDDs. It tops out around 550 MB/s, which is noticeably slower than NVMe but perfectly fine for everyday computing, secondary storage, or budget builds. SATA SSDs are widely compatible with older systems that predate M.2 slots.

Form factor is the drive's physical size and shape. M.2 is a slim stick used by most modern SSDs. 2.5″ is the standard laptop drive and SATA SSD size.

M.2 is the slim, stick-shaped form factor used by modern SSDs. It slots directly into your motherboard with no cables needed. Most M.2 SSDs use PCIe/NVMe for maximum speed, but some use SATA. The most common size is 2280 (22 mm wide, 80 mm long).

The 2.5″ form factor is the standard size for laptop drives and SATA SSDs. It connects via a data cable and sits in a drive bay. Most SATA SSDs use this size, and it fits in any system with a 2.5″ bay or a compatible adapter.

How fast data can be read from the drive, measured in megabytes per second (MB/s). This is the number most prominently advertised and the one you feel in day-to-day use: booting Windows, opening apps, loading game levels. Higher is better.

Storage capacity is measured in gigabytes (GB) or terabytes (TB). 1 TB equals 1,000 GB. For reference: a typical game is 50 to 100 GB, a 4K movie is around 50 to 80 GB, and a large photo library might be 200 to 500 GB. More capacity always costs more, but the price per GB drops as drives get larger.

NAND flash comes in different cell types depending on how many bits each cell stores. TLC (Triple-Level Cell) stores 3 bits per cell and is the mainstream choice, a solid balance of speed, endurance, and price. QLC (Quad-Level Cell) packs in 4 bits per cell for a lower cost per gigabyte, but with somewhat slower sustained write speeds and lower endurance. For most everyday use the difference is barely noticeable. QLC only becomes a real drawback under heavy, sustained write workloads.

A DRAM cache is a small pool of fast memory on the SSD that stores the mapping table telling the drive where data actually lives on the NAND chips. Drives with a DRAM cache generally deliver more consistent performance, especially under heavy or random workloads. DRAM-less drives skip this chip to cut cost, instead borrowing a slice of the host system's RAM (a technique called HMB, or Host Memory Buffer), a reasonable trade-off for lighter everyday use, but a step down for demanding workloads.

Sony's PlayStation 5 has an M.2 expansion slot for NVMe SSDs. The PS5 supports both Gen 3 and Gen 4 drives, but Sony recommends a sequential read speed of at least 5,500 MB/s to get the most out of it. A heatsink is also recommended. Some drives include one, others require you to add one separately.

High-speed NVMe drives, especially Gen 4 and Gen 5, generate significant heat under load. A heatsink is a metal fin that sits on top of the drive to dissipate heat and prevent thermal throttling, which is when the drive slows itself down to cool off. Some drives ship with a heatsink included, others need one added separately.