My PC keeps crashing and I don't know why

I built my PC in early 2020 or late 2019, shortly after the 30 series graphics cards came out. Up until about 4 months ago, my PC has been working more than perfectly. It can take anything that I throw at it. Now, when I play a simple, non graphic intense game, such as fortnite, my computer crashes. It has gotten worse over the last month, as I have returned to the gaming scene. I don't know why this keeps happening. By crashing, I mean like everything shuts off immediately, no blue screen. I have tried troubleshooting, such as opening the case, checking air flow (I have 5 case fans, 2 intake, 3 outtake), and changing the plug location. I originally thought that the problem was that the system was overheating, but now I am inclined to think it is deeper than that. Now I think the problem lies in the power supply, but I'm not completely sure. I am honestly kind of scared to open up my computer to look at the wiring, though I really hope that there is no power short happening. It is extremely frustrating, and I would love some insight on what y'all may think might be my problem.