Attach the included beeper and then look up the beep code. That can narrow the problem down a lot. Try switching the RAM to different banks, try it with one stick, etc. That can help in some cases. Right now, the most likely problem seems to be either the motherboard (those things can fail pretty quickly) or your power supply. Do you have any like electrical test equipment (e.g. Multimeter, scope, etc) ready? test the voltages.