That or plugged into the SP3 POWER brick... basically anything that can supply USB power. The 4 port hub power supply says it supplies 2.5A if that wont power your drive there's something wrong with one or both. I think the Surface USB port only supplies the required 900ma of power per the USB 3.0 std. I think 1.2A is the required minimum for a "USB Power Port". Some devices will supply more than that but it's optional and completely up the them what it supplies or needs.