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 so close to existing Ultra ATA/133 speeds, the increase in real-world performance is negligible for first generation SATA, though prices of the drives are 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 are widely available to accommodate both types of drives, and there are no restrictions to using both types in the same system. Serial ATA is also a good choice for RAID and is earmarked to eventually replace PATA.
For older systems, third party SATA controllers can be placed in any PCI slot, should you purchase a SATA drive. (A parallel Ultra ATA drive can also be used via a PATA-to-SATA adapter, though drive performance will take a hit, as the adapter must translate the data stream from parallel to serial.)
If upgrading your motherboard, buying SATA-enabled will allow ease of use for future SATA drives even if your current drives are standard ATA.
Note: When using some third party devices or adapters support for hot-swapping may be lacking or "quirky." It is always wise to backup valuable data before risking loss.