Alienware x51 r2 problem

Hi so I posted my problem on this forum not to long ago. But basically I've had my Alienware x51 r2 for roughly 2years then one day it just died on me. And we'll I wanna try and fix it myself before I send it in since my warranty ended last year.

I didn't a small components test leaving my gpu in the fans spin on and the power light stays on. I unplug the gpu and the entire system just keeps turning on and off on its own.

I got a reply saying it sounds like my power board and I replaced it and it turned out it wasn't the problem. Luckily I can return and get a refund for the part but anyone have any idea what it could be or do you feel I should just send it in somewhere.