After trying to upgrade a friends computer, adding a new DVD- CDRW combo, I got no screen on the monitor. Nohting came up not even the BIOS, and the monitors light turned yellow. I tried it on 2 monitors and the same problem. He mentioned that during unplugging his computers connections, he was pulling on the Monitors wire, the one connected on the computer. Could it be that he messed up his video card, or motherboard by doing so?