The PCI-Interface board is needed to connect the camera to your computer. There are two different PCI boards available which may be used with the Leica DC250 camera. The PCI3 board contains only one camera connector called "Camera". The PCI4 board contains 2 camera connectors called "Cam1" and "Cam2". Only the camera connector called "Cam1" on the PCI4 board is supported (the second connector from top). Please note: it is not possible to use more than one of the PCI boards inside your computer. Caution: Other PCI-boards may use the same connector (RJ45). Connecting the Leica camera to any other board may seriously damage the Leica DC camera or the computer.