Aurora R8, suddenly won't power on, #2

I have an Alienware aurora R8 that wont start up. It has power to the PSU but the front button wont turn on. i can press the button and hold on the back of the PSU and it'll light up green and spin the fans and GPU fan but wont boot up. as soon as i let off it turns the light off. opened the case and saw nothing visibly wrong, unplugged everything and plugged it back in and still nothing, cleaned everything while i was in there just to make sure. I saw something on another thread that says it may be the CPU or mother board but i wanted to make sure before I try anything else. It was working fine the night before and i hadn't touched anything.