Hi. I bought a used computer (not a lot). It have geforce gt 9600. That vga have two dvi connectors. My monitor have vga and dvi connectors. When I pluged to vga monitor not showing that there is no signal but he's just look like off, but the energy wire is connected. When I tested with gts 250 1gb with same monitor and same dvi connection and it worked fine. DVI cable is new. So what's a problem here?