What Is SATA 6Gb/s? (with pictures)

Margaret Lipman

SATA 6Gb/s is the third-generation of SATA, the predominant interface standard for connecting a computer’s host bus adapter to data storage drives. Specifically, SATA 6Gb/s ports are used to connect the motherboard to data storage units such as hard drives, solid state drives, and optical disc drives. Although the terms are technically incorrect, SATA 6Gb/s is sometimes referred to as SATA III or SATA 3.0, as it is the third revision of the SATA interface.

A SATA 6Gb/s cable is commonly used to connect hard drives.
A SATA 6Gb/s cable is commonly used to connect hard drives.

SATA stands for “Serial ATA” or “Serial Advanced Technology Attachment.” The “6Gb/s” refers to the fact that this SATA version supports maximum data transfer speeds of 6 gigabits per second, which is twice the speed of the previous generation (3 gigabit per second). Regardless of their generation, SATA cables have a maximum length of one meter (3.3 feet) and connect a motherboard socket to a single hard drive.

The third-generation of SATA technology supports data transfer speeds up to 6Gb/s.
The third-generation of SATA technology supports data transfer speeds up to 6Gb/s.

Serial ATA (SATA) vs. Parallel ATA (PATA)

When it was introduced in 2000, SATA technology changed the landscape of hard drive technology by switching from wide Parallel ATA (PATA) data cables and connectors to narrow serial cables and connectors, paving the way for faster speeds than parallel technology could handle. The use of SATA cables also physically reduced obstructions inside computer cases, thus allowing for greater air flow, faster computer processing units (CPUs), and higher capacity disk drives.

A seven-pin SATA cable.
A seven-pin SATA cable.

Other advantages over PATA include more efficient data transfer, lower power requirements, and greater affordability, as SATA requires far fewer conductors than PATA. Unlike PATA, SATA also features hot plugging, allowing computer users to add or remove devices while the computer is running. SATA has now replaced PATA in nearly all laptop and desktop computers.

The SATA 6Gb/s interface allows data transfer between the host bus adapter and a variety of different storage drives.
The SATA 6Gb/s interface allows data transfer between the host bus adapter and a variety of different storage drives.

Revisions to the SATA Interface

  • The first revision of SATA, also known as SATA 1.5Gb/s (or incorrectly as SATA I or SATA 1.0), was released in 2003. SATA 1.5Gb/s interfaces communicate at a native transfer rate of 1.5 Gb/s. This equates to a maximum uncoded transfer rate of 1.2 Gb/s, or 150 MB/s. Initially, the fastest PATA interfaces (such as PATA/133) could compete with SATA 1.5Gb/s, but PATA was reaching the limits of its clunkier architecture, whereas SATA was undergoing further improvements.
  • Released in 2004, the second generation of SATA was SATA 3Gb/s (erroneously referred to as SATA II or SATA 2.0). Second-generation SATA technology, which is backwards compatible with legacy SATA systems, doubled the native transfer rate to 3 Gb/s and the maximum uncoded transfer rate to 2.4 Gb/s, or 300 MB/s. Notably, SATA 3Gb/s introduced Native Command Queuing (NCQ), which was not supported by SATA 1.5Gb/s.
  • The third revision of SATA, known as SATA 6Gb/s, was released in 2009. The third-generation of SATA technology supports transfer speeds up to 6Gb/s, which is equivalent to a maximum uncoded transfer rate of 4.8 Gb/s, or 600 MB/s. SATA 6Gb/s has doubled the theoretical burst throughput of SATA 3Gb/s, while still remaining backwards compatible with SATA 3 Gb/s and even SATA 1.5Gb/s, as it uses the same cables and connectors. Other improvements in SATA 6Gb/s relate to additional NCQ commands and improved performance of high-bandwidth applications, such as video streaming quality. Although further fine-tuning of the SATA 6Gb/s standard has occurred over the last decade, SATA 6Gb/s remains the most recent generation of architecture.

Is the SATA 6Gb/s Interface Compatible with Older Ports?

As previously mentioned, SATA 6Gb/s is fully compatible with previous generations of SATA technology, including motherboards that support the SATA 3Gb/s or SATA 1.5 GB/s interface. However, you should be aware that the maximum read and write speeds of a SATA 6Gb/s drive are likely to be reduced when connected to a SATA 3Gb/s or SATA 1.5 Gb/s port.

In some cases, you may be able achieve comparable transfer speeds with both SATA 6Gb/s and SATA 3Gb/s cables. Sometimes, the quality of the cable and the materials used may be just as important as the SATA specification.

A quick note about terminology:

The Serial ATA International Organization (SATA-IO), which designs and manages SATA standards, has requested that the third-generation of SATA be referred to as SATA 6Gb/s, rather than SATA III or SATA 3.0, in order to avoid potential confusion with the second-generation of SATA, which is officially known as SATA 3Gb/s, in reference to its transfer rate.

A SATA cable connects a socket on the motherboard to a single storage device.
A SATA cable connects a socket on the motherboard to a single storage device.
Margaret Lipman
Margaret Lipman
Margaret Lipman is a teacher and blogger who frequently writes for EasyTechJunkie about topics related to personal finance, parenting, health, nutrition, and education.

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Discussion Comments

anon324170

When a manufacturer says a drive will reach 6Gb/s that means 6 gigaBITS, not bytes! That translates to 600 megaBYTES per second. Hard (platter) drives cannot reach that speed on their own. Manufacturers are engaging in false advertising and while lately they have been putting the words "up to" on them, they are still misleading consumers!

anon305911

I have a new 2TB seagate sata drive that is SATA 6 Gb/s. But my Intel Rapid Storage Technology service shows that the drive is running at 3 Gb/s. How can I configure it differently to run at 6 Gb/s?

anon302864

I can only agree with the above, however here are my thoughts about solid state drives. It is a fact that these drives will be the fastest drives on the market. My concern is their lifespan. As we know, SSD cards are limited to their total number of writes to one cell. The same applies to the solid state drive. To my knowledge, there is a certain algorithm used to ensure, let's say a round robin is used to spread the write cycles. Whoever constantly updates the data will probably be very unhappy. The drive will run out of life fairly soon. Unless this is a reasonably long time, it's simply not ready.

anon148113

@scienceguy34 >> Wrong, because usb has a total of 6GB/s for all devices whereas SATA will have 6GB/s for each device.

anon124325

In fact speeds of SATA 6 are not even adequate for the current drive controllers from SandForce. They have just blown past the top speed of SATA 6 with their newest SF-2000 chip. Now everything is going to go through the 4 Lane PCI Express connector on the motherboard 4x PCIe here we come.

scienceguy34

@mcsquare: Ditto on the SSD drives replacing the traditional platen hard drive. It’s already happening.

Personally, I think the fact that the new version of USB is essentially equal in bandwidth to SATA 6Gb/s will end up making SATA 6Gb/s obsolete. Instead of having SATA connections on the motherboard, there will just be more USB 3.0 sockets to which internal hard drives can be connected to—after all, USB 3.0 will have all of the capabilities that SATA 6Gb/s will have, possibly even more.

Consumers generally demand that their devices become more universal and more compatible with other technology, which necessitates a small number of connection protocols. If there are two equal protocols for attaching a device, one of them will dominate the other rather than both coexisting.

mcsquared

@AstroTurf >> True, traditional hard drives made out of platens, or metal disks, have inherit limitations to their speed. However, solid state disk drives have already pushed the current SATA speed limitations to the edge.

In the next decade, you will see the SSD (solid state disk) play a huge role in computing and will eventually replace the traditional platen hard drive. Solid state disks absolutely need a protocol like SATA 6Gb/s in order to reach their full potential.

AstroTurf

This is another example of technology getting ahead of itself. The limits of transfer bandwidth are already limited by how fast the hard drive platens can spin. Even in a 10,000 rpm hard drive, the transfer rate will not have the potential to get anywhere near the current SATA limitations.

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