Having issues when launching game

[Nate106]

Hello everyone! 

I just recently had an issue where I would try and launch a game and everything goes dark. It started off while I was playing one day and it was like something just broke! I all of a sudden lost connection to everything such as monitor which would show no display and the keyboard would stay lit up, but unresponsive. The weird part is the tower continues to stay on and even the fans are running with the exception of the front chassis fan which also stopped working. I end up having to hard shutdown and I'm just brought back to the login screen after powering back on. I've tried sending it to Geek Squad twice and they said it could possibly be the power supply or motherboard. I even switched the power supply out myself and it was still doing the same thing. Should I go ahead and attempt to get the motherboard? I feel that I don't really have enough signs that point towards it such as a blue screen of death and nothing looks burnt or brown on the inside. The issue really only happens when I try to launch a game or using something intensive such as the heaven benchmark. I'm able to do everything else including schoolwork just fine. Any other suggestions would be appreciated because I have only had this pc for a little over a year and my warranty expired only 3 months ago!