Background and Identification
SATA cables are used in computers to transfer data to and from hard drives, SSDs, and optical drives. Most desktop computer motherboards since 2003 when the SATA specification was introduced have at least one (usually more) SATA port on them. Storage devices that support SATA also have SATA ports, and you can use a SATA cable to connect the two. Many laptops also support SATA and have hard drives/SSDs inside that use the SATA connection for data transfer.
Data vs. power
SATA cables come in two basic categories: data and power. The type described in the paragraph above are SATA data cables. They allow data transfer to/from a storage device. Since the data cables don’t carry any power, the storage device requires a second cable in the form of a SATA power cable. In desktop computers, you generally connect the SATA power cable directly from your internal power supply to the SATA drive. See this installation video on YouTube for an example. Laptops usually have a single cable that puts the SATA data and SATA power connectors side-by-side so you can easily attach both plugs to the sockets on a drive. You can see a good example of this combo-style cable in a MacBook Pro drive repair guide.
History and revisions
SATA stands for “Serial ATA.” It was designed to replace the older storage communication standard called “ATA” or “Parallel ATA” (PATA) for the sake of clarity after the introduction of SATA. While PATA cables for storage connections use 40 or 80 wires, SATA only uses only seven but still achieves much faster transfer rates. The dramatic reduction in cable complexity allows SATA cables to cost much less than their older PATA counterparts.
With the original specification from 2003, SATA could push up to 1.5 Gbit/s at a maximum. These speeds were doubled twice in 2004 and 2008 to 3 Gbit/s and 6 Gbit/s respectively. In common use, the first revision is called SATA I, the second revision is called SATA II, and the third revision is called SATA III. You can see these revisions in the specifications section below. Each revision is backwards compatible with the last, meaning that you can use a SATA III drive with a SATA I computer, although the speed will be limited to the lowest standard between the pair (1.5 Gbit/s in this example scenario).
Extra uses of SATA
The eSATA cable was standardized in 2004 as an external version of SATA. It uses a different connector meant to sit on the outside of your desktop computer or laptop. You can buy eSATA to standard SATA cables that allow you to connect a drive directly to your computer’s eSATA port. This port is not very common on modern computers, but you may still find it on some devices made in the 2000s and 2010s.
In 2009, the SATA committee designed the mini-SATA form factor (mSATA for short). SSDs that use this form factor are built on a small, thin circuit board that plugs directly into a slot on a computer’s motherboard. The slot is exactly the same as the PCIe Mini-Card slot, but a computer needs to explicitly support mSATA drives because the two formats are not interchangeable. Grr!
mSATA has largely been replaced by the M.2 form factor. SSDs in the M.2 form factor are also built on thin circuit boards, but the M.2 slot they fit into is distinct from the mSATA slot. While some SSDs use the faster NVMe communication standard, other M.2 SSDs still utilize SATA. Basically, M.2 is the name for the physical slot you plug the SSD into; NVMe and SATA are the methods for communication, with NVMe being much faster than SATA. This is a confusing distinction that often trips people up, but now you know the difference.
Technical Specifications
Transfer speed
- SATA I: 1.5 Gbit/s
- Actual speed of 150 MB/s
- SATA II: 3 Gbit/s
- Actual speed of 300 MB/s
- SATA III: 6 Gbit/s
- Actual speed of 600 MB/s
- SATA Express: 16 Gbit/s
- Actual max speed of 1969 MB/s
- Hardly any drives have this connector, so it’s a bit useless