Ideally you need an internal USB Socket, because the this bay has a connecting cable with a normal USB plug on it. No need for a power supply as it gets power from the internal USB socket. I decided to update an ageing PC by installing a USB 2.0 PCI card and a front loading hub. This worked a treat. The PCI card has five USB sockets, four external, one internal. Removed the blanking plate from a spare 3.5 slot and the bay slid into place. It is a close fit, and to ease matters I did bend slightly inwards the internal case metal at either side with a pair of pliers. Not much of a problem really. Result, a neat fit which is flush with the other 3.5 bay (and in fact the 5.25 bays as well). The operating system detects the hub and installs the drivers. The bay has two LED's one red, which is the power, and the other green which lights when the OS detects the USB's.