If you’re in the market for a new SSD to boost your computer’s performance, then you really need a firm grasp of the different types of SSD interfaces and protocols available to you.
Otherwise, you might buy a drive that isn’t compatible with your motherboard.
To prevent this from happening to you, we discuss SSDs, interface types, and the protocols they adhere to below.
But before we begin…
What exactly is an interface?
An interface is the physical point of contact between one thing and another. In this article, we’re talking specifically about your motherboard and SSD.
While the type of interface will vary depending on your motherboard, all interfaces consist of a plug and socket design.
The socket is embedded on your motherboard, and the plug is attached to your drive. Both the plug and socket have specific pin configurations (called a pinout) that define how data is transmitted between both devices.
For the two connections to be compatible, not only must the pins correspond, both your device and SSD must adhere to the same interface specification, also known as a protocol (we discuss these more below).
Now that we’ve clarified what an interface is, let’s dive in to the different types of interfaces out there.
Want to learn more about storage technology? Our comprehensive SSD guide covers what you need to know, and more!
#1. SATA SSD Interface
SATA is an interface that is compatible with SATA-based HDDs and SSDs. The most current SATA iteration is SATA III, which delivers transfer speeds of 6Gb/s and usually comes in a 2.5” form factor.
Since its arrival on the market in 2003, SATA has undergone several revisions to keep up with the performance demands of SSD technology.
Here is a list of all SATA revisions to date, in case you’re interested.
#2. mSATA SSD Interface
SATA Revision 3.1 introduced mini-SATA (mSATA) to mobile computing devices like laptops and utlrabooks in 2011. The mSATA connector looks similar to that of a PCIE Mini Card connector, but is not functional if plugged into a PCIE slot.
Although you can still find mSATA SSDs, the better designed M.2 has ultimately replaced them (more on M.2 interfaces below).
#3. SATA Express Interface
SATA Express (SATAe) came about under SATA Revision 3.2 and is compatible with both SATA and PCIE drives. The host connector (the socket on your motherboard) can fit two SATA 3.5” drives or two PCIE SSDs, depending on what kind of speeds you’re looking for.
For a SATA-based drive, SATAe broke the former speed limitations of its forebears, offering up to 10Gb/s.
However, it should be noted that the SATAe specification is now obsolete.
So, why include it?
Back in 2014, a limited number of PC motherboards were manufactured with compatible SATAe interfaces.
Specifically, the socket was created to give end users the option of using SATA- or PCIE-based drives. However, this implementation became unnecessary with the advent of the M.2.
We thought it necessary to include this info in the event that you somehow managed to get your hands on one of these PC motherboards. Now, you know what to look out for if you do.
Most consumer laptops and PCs come equipped with an M.2 drive. Check your manual before you upgrade to get the specs right!
#4. PCIE SSD Interface
Your computer’s Peripheral Component Interconnect Express (PCIE) interface connects to PCIE devices, allowing for faster communication between the device and your motherboard.
PCIE slots can contain anywhere from X4 to X16 lanes (or more) depending on your motherboard. PCIE SSDs connect to these slots, allowing them to achieve blistering transfer speeds that easily outstrip the best SATA drives.
A PCIE 2.0 drive, for example, can achieve 2GB/s with just one PCIE lane. If your motherboard contains X4, X8, or X16 lanes, it’s easy to imagine the speeds you can reach with multiple PCIE drives.
#5. M.2 Connectors
Originally called the Next Generation Form Factor (NGFF), M.2 connectors can be found on both mobile devices and PC motherboards. M.2 connectors are also compatible with both SATA III and PCIE devices, making them more versatile.
Of course, if there is a connector, then there must also be a device. M.2 drives can be either SATA or PCIE specific and are considered the future of solid state form factors.
M.2 form factors are measured in millimeters (mm), which is included in the product name. For example, a common M.2 shape is 2280, or 22mm X 80mm (width-length). The drive would be listed as M.2 2280 SSD.
Here is a list of M.2 form factors:
To determine which M.2 drive is compatible with your motherboard, you need to look at your motherboard’s manual. Most modern motherboards accept 2280 M.2 drives or shorter.
If you’re looking to purchase a new M.2 drive, you should check which protocol your motherboard supports, along with the form factor.
For example, if your motherboard has a M.2 2280 SATA interface, your M.2 2280 PCIE drive will fit like a glove, but not function.
2 SSD Protocols to Be Aware of
Protocols enable your devices to communicate. The interface is the means for communication, and the protocol provides the commands that detail how data transfers are to be carried out between devices.
There are two main protocols out there:
Advanced Host Controller Interface (AHCI) is a protocol that allows your computer to communicate with your SATA-based drive via software. As a SATA-specific protocol, AHCI works with both SATA-based SSDs and HDDs.
Non-Volatile Memory Express (NVME) is a protocol tailored specifically to non-volatile memory i.e. NAND Flash, or solid state drives, with a PCIE bus (or connector). NVME is only compatible with PCIE-based drives, so an M.2 SATA drive wouldn’t work.
Have questions about NAND Flash memory? We’ve got answers. Learn more about SLC, MLC, & TLC NAND Flash memory technology here.
What are the performance differences of AHCI and NVME?
NVME SSDs are performance drives. In the past, protocols limited SSD capabilities, offering only a fraction of the performance enhancements they can provide to users.
The NVME protocol enables your computer to process commands — referred to as Input/Output Operations Per Second (IOPS) — at an unprecedented rate.
To get a better idea of how this works, think of the interface connecting your devices as a lane. With older protocols (AHCI), SSD’s could only use one lane — called a command queue — for inputs and outputs (the commands that tell the data what to do), resulting in what we call latency, or “lag.”
The NVME protocol offers more lanes and a direct connection to your CPU, which essentially “unclogs” your drive’s command queue.
How drastic is the difference between AHCI and NVME?
AHCI can process up to 32 commands with one command queue.
NVME has up to 65,000 command queues with up to 65,000 commands per queue.
This has two major performance benefits:
- It significantly decreases latency;
- It dramatically improves transfer speeds
As we mentioned earlier, all NVME drives utilize the PCIE interface, so finding the right drive to deliver the speeds you want is a matter of making sure both your PCIE interface and SSD support the NVME specification.