The majority of flash drives use USB, but some flash drives use other interfaces, such as IEEE1394 (FireWire), one of their theoretical advantages when compared to USB drives being the minimal latency and CPU utilisation that the IEEE1394 protocol provides, but in practice because of the prevalence of the USB interfaces all IEEE1394-based flash drives that have appeared used old slow flash memory chips and no USB flash drive manufacturer sells IEEE1394 flash drives with modern fast flash memory as of 2009, and the currently available models go up only to 4GB, 8GB or 16GB, depending on the manufacturer. FireWire flash drives that needs to be connected to FireWire 400 port cannot be connected to a FireWire 800 port and vice-versa.
In late 2008, flash drives that utilize the eSATA interface became available. One advantage that an eSATA flash drive claims over a USB drive is increased data throughput, thereby resulting in faster data read and write speeds. However, using eSATA for flash drives also has some disadvantages. The eSATA connector was designed primarily for use with external hard disk drives that often include their own separate power supply. Therefore, unlike USB, an eSATA connector does not provide any usable electrical power other than what is required for signaling and data transfer purposes. This means that an eSATA flash drive still requires an available USB port or some other external source of power to operate it. Additionally, as of September 2009, eSATA is still a fairly uncommon interface on most home computers, therefore very few systems can currently make use of the increased performance offered via the eSATA interface on such-equipped flash drives. Finally, with the exception of eSATA-equipped laptop computers, most home computers that include one or more eSATA connectors usually locate the ports on the back of the computer case, thus making accessibility difficult in certain situations and complicating insertion and removal of the flash drive.