Random Black screen?

I'm not entirely sure what causes this but, I have Madden 26 on Steam and am playing a Bears franchise (#beardown) but randomly in the middle of games, or while im in practice mini camps or any form of gameplay, my screen will black out and my computer will shut down. I'm not entirely sure as to how to fix it as ive tried re-installing, updating my drivers, closing overlays and all but I fear it might be a Power supply issue and I hope its not. If anyone has any ideas, please help