Basic Concepts About SATA III

SATA III is the standard interface in the modern motherboards for hard disk drives, solid state hard drives, and DVD-ROM drives. And as a computer user who look forward to educating yourself about your machine, this article will help you better understand this type of technology.


The SATA series of adapters are a new type of connection between the hard drive and Motherboard drastically improving transfer rate and a far better multitasking rate the higher the series.

SATA III, or SATA Revision 3.x, is the next set of specifications following the original SATA and SATA II storage interface specifications. SATA III doubles the maximum data transfer rate for previous Serial ATA storage interface specifications from 3 to 6 Gigabits per second (6 Gb/s), enabling faster data transfer speeds between storage units, hard drives, solid state disk drives, optical drives and protocol host bus adapters (HBAs).

Before we dive deeper into this topic, we need to go back and look into the history of Serial ATA controllers.

SATA Is The Successor Of PATA

Anyone who has peered into a computer is familiar with the flat, 40-wire parallel cables that connect the hard drive, CDROM and other devices to their controllers. PATA has been the standard and has served well, but it has also had drawbacks. Cables limited to 18 inches (46 cm) in length often made connections difficult and also clogged cases blocking airflow, while cooling has become crucial. Though rounded cables became available, the most advanced PATA drives (Ultra ATA/133) hit the maximum parallel transfer rate of 133 MB/ps. With the speed of CPUs, RAM and system buses improving, designers saw PATA would soon be bottlenecking advanced drive efficiency in system architecture.


Serial ATA has distinct key advantages over its predecessor. Cables are very thin with small 7-pin connectors. They can be up to 3 feet (1 meter) in length, and are easily routed to stay out of the way allowing maximum airflow inside the case. SATA also has a far lower power requirement of just 250 mV compared to PATA’s 5-volt requirement, and with chip core voltages declining, this speaks well of SATA’s future. Serial ATA does away with Master/Slave configurations and drive jumpers. Setup is greatly simplified, and the technology even allows hot-swapping, meaning drives can be removed or added while the computer is running.

However, the most promising feature of Serial ATA is that it eliminates the transfer limit hit by PATA. First generation has a maximum transfer rate of 150 MBps, and second generation SATA delivers about 300 MBps. A third generation SATA set for 2009, “SATA 6Gb/s” will deliver roughly twice the speed of the previous SATA iteration.

With introductory transfer speed, the increase in real-world performance was negligible for first generation SATA, though prices of the drives were comparable to PATA drives, making the switch to the new technology a good choice when upgrading, building, or buying a new system. Motherboards with integrated SATA and PATA interfaces were widely available to accommodate both types of drives, and there were no restrictions to using both types in the same system.

But now, most motherboard manufacturers stopped including PATA interface into their into their new builds, rapidly expediting the extinction of it.

Serial ATA is also a good choice for RAID and is earmarked to eventually replace PATA.

Terminology: “SATA III” or “SATA Revision 3.x”?

In an effort to resolve confusion over the specifications, the Serial ATA International Organization (SATA-IO), the organization formed to author the SATA specifications, has encouraged the use of SATA 6Gb/s or SATA Revision 3.x instead of the moniker SATA III. The confusion stems from the 3 Gb/s data transfer rate of SATA II vs. the 6 Gb/s rate of the newer specification.

SATA III Biography:

Serial ATA International Organization presented the draft specification of SATA 6 Gbit/s physical layer in July 2008, and ratified its physical layer specification on August 18, 2008. The full 3.0 standard was released on May 27, 2009. It provides peak throughput of about 600 MB/s (Megabytes per second) including the protocol overhead (10b/8b coding with 8 bits to one byte). Solid-state drives have already saturated SATA 3 Gbit/s with 285/275 MB/s max read/write speed and 250 MB/s sustained with the Sandforce 1200 and 1500 controller. SandForce SSD controllers released in 2011 have delivered 500 MB/s read/write rates, and ten channels of fast flash can reach well over 500 MB/s with ONFI drives – a move from SATA 3 Gbit/s to SATA 6 Gbit/s allows such devices to work at their full speed. Full performance from Crucial’s C300 SSD similarly require SATA 3.0. Standard hard disks cannot transfer data fast enough to require more than 3 Gbit/s; but they can nevertheless benefit from the later standard as reads from their built-in DRAM cache will be faster across the later interface. According to Seagate “Cache-efficient desktop applications such as gaming, graphics design and digital video editing can experience immediate incremental performance using a SATA 6Gb/s interface”. Drives with bigger, faster caches were introduced to benefit from the faster interface.

A Quick Comparison between SATA-I, SATA-II, And SATA-III

The difference between the I, II, and III is speed (Transfer rate). Series-I have a transfer rate of 1.5 GB/s (But only in short burst with a typical rate of 1.2 GB/s, series-II a rate of 3 GB/s and finally series-III a transfer rate of 6 GB/s.

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