Have you overclocked it by any chance? If so you might of not put the power frequency up on your power supply which can seem like your computer is working fine but if you have overclocked it too much with little power going to the cpu then it wont work. If this isn't the case then im not too sure as i dont know much about computers i can link you to a video where a guy overclocks with not enough power from the power supply. click here
This thread is now locked and can not be replied to.