Question PC Randomly Shuts Off, Freezes, or Stops Outputting Video

[Gosraj]

This has been happening very occasionally for a while now when I'm just on the internet or playing a low intensity game, but I recently just saw that Destiny 2 is free on Steam, so I picked it up, and now these problems are completely keeping me from playing it. Every time I open it, within like 5 minutes, one of these things happen. When it randomly shuts off, well, it's pretty self explanatory. The PC turns off without me pressing the power button, unplugging the PSU, nothing like that. When it freezes, it completely freezes while still playing audio, and the only thing I can do is force shutdown my PC, nothing like alt+F4 or ctrl+alt+delete helps. And when it stops outputting video, my screen goes off for a sec, my monitor tells me that there's nothing connected, and when it reconnects I'm on my desktop, but the game is minimized and inaccessible, which I then have to close using task manager.

I've dealt with the occasional ones for a while now but this is getting out of hand. I'm assuming these are all a connected issue, and I hope it's an easy fix, so if anyone knows, please do tell! Thanks!

 

[Gosraj]

This is a probably separate problem, but I figured I might as well add it, but like 5 or 10 seconds after I boot up my pc, my keyboard and mouse won't input anything for another 5-10 seconds, and then work like normal. It's not like ruining my PC or anything, it's just a tad annoying.