Understanding M.2, SATA, PCIe and NVMe SSDs

Upgrading your memory can be confusing, especially with evolving technologies, increasing options on the shelf, and numerous acronyms. At Crucial, we’re here to help. We want you to feel comfortable upgrading or building your own PC, or even just understanding the specs of your current set-up.

Not all solid state drives (SSDs) are the same, and there are some key elements that determine compatibility, speed, and price. This article explains the M.2 form factor, the differences between PCIe vs. SATA and what exactly NVMe means. With this information, you’ll make more informed decisions about which SSD is right for you.

An M.2 SSD is a solid-state drive that uses the M.2 form factor, which is a small, rectangular card-like shape. It's designed to be faster and more compact than traditional hard drives, making it ideal for use in laptops and desktops where space is limited and speed is crucial.

M.2 is a form factor specification that was introduced in 2012 and designed to replace the mSATA standard. The form factor specification spells out the physical size and shape of the SSD card you can connect to your system. The M.2 form factor is designed to maximize PCB (printed circuit board) while minimizing the amount of space it takes up in your PC or laptop. To connect an M.2 specified SSD, your motherboard will need to have an M.2 slot.

The M.2 form factor is small and rectangular in shape, almost like a piece of gum. Sizes can vary, with possible widths of 12, 16, 22, or 30 millimeters, but they’re generally 22 millimeters wide. Lengths can also vary, coming in 16, 26, 30, 38, 42, 60, 80, or 110 millimeters. Motherboards will accommodate a variety of lengths for an M.2 module to allow for flexibility, while the width is more fixed.

When you buy an SSD like the Crucial T500, you may see something like "M.2 2280" in the title, which is a combination of its dimensions — 22mm and 80mm in length — helping you know what to buy.

When comparing M.2 SATA SSDs to M.2 NVMe SSDs, it's essential to understand the underlying technology and how it impacts performance. M.2 SATA SSDs utilize the SATA interface, a widely used standard in storage devices. This interface, while an improvement over traditional hard drives, has its limitations. M.2 SATA SSDs can achieve speeds comparable to their 2.5-inch SATA counterparts, typically reaching around 550-600 MB/s for sequential read/write operations. While faster than HDDs, this speed is capped by the SATA interface's bandwidth.

On the other hand, M.2 NVMe SSDs leverage the PCIe (Peripheral Component Interconnect Express) interface, designed specifically for solid-state storage. PCIe offers significantly higher data transfer speeds compared to SATA, allowing NVMe SSDs to achieve much faster performance. NVMe SSDs can often surpass 5000 MB/s for both read and write operations, with the Crucial T705 reaching  14,500 MB/s thanks to the high-speed PCIe lanes enabling rapid communication between the SSD and the rest of the system.

The performance gap between M.2 SATA SSDs and M.2 NVMe SSDs becomes evident in demanding tasks such as gaming, content creation, and professional workloads. NVMe SSDs excel in scenarios where speed is paramount, offering quicker load times, faster file transfers, and improved overall system responsiveness. However, it's worth noting that for everyday computing tasks like web browsing and document editing, the difference in performance may not be as noticeable.

Now we know that the M.2 form factor dictates what type of memory drive we can connect; our next job is to understand SSD interfaces.

In general PC building terms, an interface connects two or more separate components to exchange data or information. The SATA and PCIe interfaces are the physical connections that transmit data from the memory storage to the computer.

SATA and PCIe aren't the only available interfaces for SSDs, although they are now the most common.

The older of the two interfaces, SATA was launched in 2003, bringing massive advancements to computing and memory storage. In the image below, you can see how a SATA interface connects to your motherboard. The original SATA interface was designed for hard drives, but when SSDs came on the market, they adopted the same interface so users could easily upgrade their storage drives.

If you have a SATA interface, only a SATA SSD, such as the Crucial BX500, will work with your computer.

PCIe (Peripheral Component Interconnect Express) is a newer interface that features a smaller physical footprint, meaning it takes up less space in your computer, as seen in the image below. The real advantage of the PCIe interface over SATA is the ability to transmit data on up to four lanes, whereas SATA only has one. When combined with an NVMe SSD, which we’ll discuss shortly, PCIe SSD read/write speeds increase even more than SATA.

The implementation of multiple lanes for the PCIe connection is one of the most essential features. PCIe uses four lanes for storage devices, resulting in data exchange that is four times faster than a SATA connection, which only has one lane. This provides faster read and write speeds, as seen in the table below -—- meaning faster gameplay, smoother multitasking and a more responsive computer.

All of these enhancements come with another benefit: reduced power consumption. The combination of NVME, PCIe, and an SSD's lack of moving parts results in a quieter storage drive that sips power, extending battery life for laptops, notebooks, and tablets.

We know that if you have a SATA interface, you’ll need to connect a SATA SSD if you’re looking to upgrade your memory, but what if you have PCIe?

NVMe (NVM Express™, or Non-Volatile Memory Express) is a communication protocol designed specifically to work with flash memory using the PCIe interface. NVMe was created to take advantage of the parallel nature of solid state drives.

NVMe SSDs combined with a PCIe interface create unrivaled read and write speeds. However, you can also get PCIe compatible SSDs that are non-NVMe.

Combining the NVMe SSD and the PCIe connection results in read and write speeds that are four times faster than a SATA interface/SSD.

NVMe complements the parallel structure of contemporary CPUs, platforms, and applications. These parallel structures allow for more commands to flow simultaneously. NVMe uses an optimized path to issue commands and complete input/output, and it supports parallel operation with up to 64,000 commands within a single I/O queue and 64,000 possible queues. Older protocols such as SCSI are serial in nature, with a limited number of commands in a single queue.

Discover our range of NVMe SSDs including the Crucial T500 2TB, 1TB, and our PCIe 5.0 SSDs.

Find out more about how to install NVMe PCIe SSDs.

Compatibility with your computer is the most important factor in choosing an SSD interface. It can be challenging to tell the difference between PCIe and SATA connections if you look at the slot on the motherboard. Check your computer specifications to see which interface your computer supports. Even easier, use the Upgrade Selector™ or System Scanner to find compatible parts.

If you have the option of multiple M.2 slots where at least one supports PCIe, it's worth considering your secondary slot for an SSD upgrade. When combined with an NVMe SSD, PCIe will result in faster read and write times.