|What you got here is probobly the motherboard related problem. Have seen it when it comes to mother boer that has been poorly assembled which has generated simular problems as yours. In some motherboards (not yours I'm afraid) a LED which errorcodes indicates type of problem which is an improvement in the right direction.|
However have you tired to use another PSU (Power Supply)?
The motherboard in another configuration? (less RAM, other RAM)
The way I understand your computer is powering of before it actually reach post in the BIOS. This itself indicates some sort of power fail, where the motherboard switch of either to protect its components or the PSU delivers wrong voltage to some motherboard cirquit.
This could also according to my Googling be result of overclocking test.
You should however the be able to come back to some sort of default value.