If you look on your motherboard, there is a code, this will most likely indicate the cause of the problem... although, the codes can be wrong. What i may suggest, maybe cpu is fried (have you overclocked at stable temperatures?), the power supply is faulty and not giving enough power to boot, ensure all cables are connected. IF NONE OF THIS WORKS, what i did when i had a similar problem was. Buy one part on amazon, swap it in my pc... if it solved the problem, i kept it. If it didn't, i would send the part back to amazon and purchase a different part that may cause the problem. This allows you to find out what is wrong without paying for shipping or a technician, this is very effective seeing that amazon doesn't charge for shipping or for returning for any products. win-win. Good luck!