Its an ECSP4M800 motherboard and it was bought almost two years ago,the system performs a POST test and base by its single beep sound plus the keyboard is responding when I press the NUM or CAPS lock button, I can tell that the system is normal . The only problem is that it has no video going to the display monitor.
I tried to install a known good monitor but the problem still the same. I install an AGP card on its AGP slot and the display comes in and tested that the unit is working fine. It was confirmed that it was a defective on board video device that is causing the problem.