Hello. So my Dell dimension 4600 just lost mointor/video signal one day. All the fans, drives and CPU were still workin away. I figured ok great my video card is blown(in my case the MB). So I install a new MB. Still no video or monitor signal....I have checked the diagnostic lights on the back and none of them are lite. I have tested the power supply - seems fine. I have unplugged everything other than the CPU, main and second power to MB. I am getting no error beeps. I am so lost here!! I need some help please!! Thanx