Un plug all drives, PCI-E, PCI, sata, ide hardware.
Leave only power supply, motherboard and CPU.
If you hear the RAM missing beep, it's most likely not the motherboard. Which means it's the CPU or RAM, try test ram on another computer if you have one. If it works it's the CPU.
If no sound beeps because of lack of ram or the computer does not boot or turn on, then your motherboard is fault. Send it to RMA if it's still in warranty, if not then your going to need to buy one.
CPU must also be tested but I doubt you have the resources to test it in.
What processor, ram, motherboard do you have?