The Difference Between SATA I, SATA II And SATA III - Simply Explained

2023 Author: Sheila Hailey | [email protected]. Last modified: 2023-08-25 04:29

The abbreviation " SATA " stands for " S erial A dvanced T echnology A ttachment" (extended serial technology connection). SATA is a technique for transferring data from SSDs and hard drives to certain mainboard components and vice versa. In the past, there were parallel interfaces, which were later converted to serial. Serial means that data is transmitted bit by bit in succession.

Mainboard connections explained

What is the difference between SATA I, SATA II and SATA III?

The various SATA levels indicate the maximum speed with which the data can be transferred. The higher the level, the faster data in the computer is transferred to SSDs or hard drives.

	SATA I	SATA II	SATA III
Year of launch	2002	2005	2009
Max. speed	1.5 Gbit / s	3 Gbit / s	6 Gbit / s
Max. Bandwidth throughput	150 MB / s	300 MB / s	600 MB / s
Designations	SATA 1.5 Gbit / s SATA I SATA-150	SATA 3 Gbit / s SATA II SATA-300	SATA 6 Gbit / s SATA III SATA-600

For comparison, a hard disk transfers in theory a maximum of 120 MB / s, more practically about 80 MB / s. So that's about half the specified SATA-I speed. This does not change if you operate the hard drive with the SATA I, SATA II or SATA III interface. An old-fashioned hard drive cannot transfer data faster for technical reasons. For this reason, SSDs were invented that can fully exploit the SATA interface.

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How fast is an SSD on SATA I, II and III?

The following guidelines apply to sequential read and write speeds. So large files are written or read in one piece:

With SATA III, an SSD achieves around 500 MB / s in reading and writing in practice.
With SATA II, an SSD achieves around 280 MB / s in reading and writing in practice.
With SATA I, an SSD achieves around 120 MB / s in reading and writing in practice.

If no other components in the computer slow down the speed, even an SSD with SATA I is faster than a hard drive (on SATA III, II or I). The following YouTube video of the channel "T Driver" shows the difference between an SSD and a hard drive with SATA I when booting Windows:

An SSD with SATA I is always worthwhile compared to a conventional hard drive if speed is important. Depending on the computer system, it can happen that you don't notice a big difference between an SSD with SATA I and a hard drive. From SATA II, however, you notice a significant increase in speed.

As a large data archive, hard drives are still one of the best storage media, since their prices are cheaper per gigabyte and data from defective hard drives can be better recovered than data from defective SSDs.

This is a SATA cable that transfers the data between the SSD / hard drive and mainboard. Image: Michael Schwarzenberger (Pixabay)

And what is "SATA Express"?

"SATA Express " was introduced in 2013 and is referred to as the SATA 3.2 interface, making it even faster than SATA 3 / SATA III. "SATA Express" transfers at 8 Gbit / s per PCI Express lane (PCIe lane). A maximum of 2 PCIe 3.0 lanes are supported, resulting in a maximum transmission speed of 16 Gbit / s.

Since the M.2 interface even supports up to 4 PCIe lanes and today's drives require higher bandwidths for maximum performance, M.2 has become already increasingly established in modern desktop PCs and laptops.