What is external hard drive speed

Next to storage capacity, speed is the most crucial quality of hard drives. The speed of a hard drive affects the overall speed of a computer’s performance. A computer with a fast hard drive will perform operations dramatically faster than a comparable computer with slower hard drive.

The overall speed (effective speed) of a hard drive is affected by three factors:

  • The speed of disk rotation
  • The type of chips the drive uses to manage data processing
  • The protocol used to connect the drive to the computer (FireWire, USB, Thunderbolt; IDE, SATA,PATA, SAS)

The disk rotation (RPM) is the most important of the three because it affects the data transfer rate which in turn affects performance. Two common rotation speeds are: 5,400 rpm and 7,200rpm. Some high-end drives have speed of 10,000 RPM.

Generally, the drive with the higher RPM will transfer data faster than another comparable hard drive. According to some estimates, “a 7,200 RPM drive will deliver data about 33% faster than the 5,400 RPM drive” other factors being equal.

In the final analysis however, what you choose depends on how you intend to use the hard drive. A good rule of thumb is to get a 7200 rpm drives for desktop computers and a 5400 rpm drive for a laptop for budget solutions and SSD in all other cases.