I was checking my email last night and suddenly my pc goes blank and restarted. After the pc restarted it shows power on but it did not post. I had seen inside the cabinet it shows that cpu fan is running, hard drive is working, power supply is also working, but there is no signal on the monitor. I am not able to figure out what happened. Then i started the pc on after a hour later it showing not sign of post. The numlock light is on my keyboard, mouse is working and usb. Recently i had added a video card in my pc. Is the video card affecting my pc. What can be reason for this.