Computer randomly restarting.

[BattleToads]

So my room mate dusted out his PC a couple days ago. After which, he said it black screened for a while, but ran ok for a couple days. Now, however, he is saying his monitors will randomly go black and the computer will restart back to the motherboard screen. I'm not sure if he accidentally knocked something slightly out of socket or other user error while cleaning or if it is his motherboard, CPU, CMOS battery, etc. What would you suggest to fix or at least narrow down to the point of failure? 

[Founders]

Double check that everything is seated properly, cables, RAM, and re-seat the video card and see if that helps improve stability. It sounds like something may have been rattled loose. 

[BattleToads]

OK, so I installed my 1050 Ti in his machine and now it won't display anything at all. It starts, you can hear the PC and fans running but no activity on the monitors. Then, it shuts off. Then, it restarts. Rinse, repeat. Dead motherboard I'm guessing?