My suggestion would be to remove the MB battery and default the CMOS jumper defaulting the BIOS. The system is old and the CPU or MB may be bad. Be sure a working speaker is connected to the front panel speaker header to sound BIOS error beep code. Remove all the system RAM and boot the computer. If BIOS does not beep indicating there is no RAM in the system, either the CPU or MB or both are bad.
I get a RAM error beep upon removing the RAM, so all hope isn't lost. I'm guessing it has to do with the PCIe Slots, and there is no on-board GFX to use, so I have tried both PCIe slots with mutiple slots. Any suggestions or ideas?