Beeps with CPU/no memory, does nothing w.CPU+mem.??!

[Kaiyosan]

I have an AT motherboard from an unknown manufacter. It has a TX chipset and 83mhz bus speed, so it'll take Pentiums and K6-2s, but it has a problem. When I install the CPU and no memory, it doesn't post and it beeps to let me know there no memory, but when I install the memory, it doesn't post OR beep. It has slots for both SDRAM and EDO, and I have tried both types with no results. Its not the CPU or RAM because i tested both the SD and the EDO, as well as both CPUs in another machine, and it posts fine. Its not the cpu voltage because the board autodetects it and sets accordingly, and i have tried various fsb and multiplier settings. I have tried using normal and ATX power supplies, and nothing, although when I use ATX power, it will come on put won't shut off after holding the button for more than 4 seconds-??. I've tried using different video cards in all its PCI slots, yet nothing. Please help, its was a fantastic classic AT overclockers board when it worked, and it was one of the few of its day that offered SDRAM,EDO,AT power,ATX power, auto-voltage, as well 83mhz bus, all on the same board. I'd hate to have to throw it away.