You can sync your screens only with an external device. We use the Datapath x4. You connected onle one DVI to Catalyst on Datapath, use one submix. And the output x4 is sent to the transmitting sender card(not scree processor input!). The datapath is necessary to put the same resolution and frequency at the output(for sync). If your sender card is understood signal triple2go you can use it. It is cheaper.