I have a MacPro with two DVI graphic cards and one monitor. I like to use a KVM switch to choose which card I'll be using my monitor with. I have tried one DVI KVM but it always left the non-active card in powered mode. Meaning, the computer would continue to recognise that something is connected. Anyone, know a working DVI KVM model which will hard switch, as in powering off the DVI path? Thanks.