What’s the difference between SCSI, IDE, and SATA?

Hard drives and other devices are connected to a computer motherboard through some type of cable. These cables use multiple smaller wires in parallel to transmit the proper signals for reading and writing to and from the drive. There are multiple types of cables, which transmit at different speeds and use different types of connectors. Here we will look at some of the most common device cables and the differences between them.


SCSI stands for Small Computer System Interface and used a parallel cable to attach both internal and external devices. One of the benefits of SCSI interfaces is that multiple devices could be chained together to a single port. Another benefit is that the interface includes features like error checking and hand shake signals between devices.


IDE stands for Integrated Drive Electronics and refers more to the standard than the cable type itself. The technology is also often referred to as ATA or PATA. ATA cables can only be up to 18 inches in length and are fairly large and flat, which makes them a poor choice for external devices, so the interface is mainly used for internal devices. The cable uses a combination of 40 or 80 wires in parallel.


SATA stands for Serial ATA and is an evolution of the original ATA (or IDE) interface. The SATA interface is faster in speed, at up to 3GB/s. Another major benefit of the interface is that the cables and connectors are much smaller, taking up less space inside a computer case and not restricting air flow. There is an external version of SATA known as eSATA for connecting external hard drives and other devices.

Interface cables have improved quite a bit over the years, but the basic concept of input and output has remained mainly the same. New interfaces such as Thunderbolt have added even faster transfer speeds and taken some of the benefits from multiple technologies to make an improved connection.