A:Answer Thank you for your inquiry! The Insignia™ 4' Micro USB 3.0 Charge-and-Sync Cable can power a 16TB Seagate external hard drive only under certain conditions. If the drive is a portable 2.5-inch model that uses a Micro USB 3.0 port and is designed to be powered solely through a USB connection, then this cable should work for both power and data transfer. However, if the drive is a desktop-class 3.5-inch model, it will require an external power source and cannot be powered by this cable alone. These larger drives typically come with their own power adapters because USB ports, even USB 3.0, do not supply enough power to run them. To determine compatibility, it's important to check the specific model of your Seagate drive. Keith | Insignia Support