NO DISPLAY on booting the PC

Hello,

Initially, there use to be some RAM problem with Long beep sound in my PC(home configured few years ago). I cleaned and reseated in it's slot. It worked fine.

Later i found that the integrated ethernet port did not function. I got a new ethernet card at PCI slot. The new one was working fine. But i do not know whats wrong with the integrated port.

Few days later, there was not display in the monitor when i switched ON. I found the OS(win xp sp3) boots well and its working fine. I tried to connect to this system via teamviewer and it was successful.

Tried rebooting the system. Unfortunately I got the same old RAM Problem(long beep sound). Again i removed it, undusted it and reseated it. now there is no Beep sound, no display either. Also, unable to ping the system from LAN. No idea whether it is booting properly or not.

Juz checked the connection of two wires (as instructed at some website - 2 yellow, 2 black) at MotherBoard, tried disconnecting and connecting of HDD, CD-drive, BIOS Battery(waited for more than 10 mins). But no solution. Till this point, i could see the POST is proper (NO DISPLAY at the monitor but with the blink of the keyboard LED).

Just to check, i removed CMOS battery and started the PC. No result. Now put the battery back and to my frustration i could not see the POST (no indications at the keyboard) as well which was working previously.

Configuration: Mercury pi865d7 version 2.0, Intel celeron, win xp, Integrated VGA.

Monitor & VGA cable working fine with other system. As NO DISPLAY, how should i proceed further? Kindly suggest me.