Windows 10: Crashing [shuts down] ONLY during gaming load with root cause undetectable

First of all, I am a computer engineer, I've tried all I could think of the past few days. I could use some help at this point. PC specs are listed down below.Crashes ONLY during gaming load with root cause undetectable.Out of nowhere, the PC started crashing [shutting down] whenever I tried to play a game.However, with zero crashes, I ran:- GPU stress-testing tool from UNIGINE at max settings multiple- Prime95 CPU stress tests for a day- MemTest86 Pro Edition v.9 [zero errors]I checked the event viewer after the crash for "Error" and "Critical" and nothing comes up on "system" or "application

:)

 

GPU-Z 0.7.5 causing crashes on load up

Any chance you could narrow it down to which running application causes GPU-Z to crash? Ideally steps to reproduce for me here.

 

all games crash!

I suggest you run rthdribl > http://www.daionet.gr.jp/~masa/archives/rthdribl_1_2.zip
Increase the window size step by step and watch your vga temps permanently.
What happens?
If it crashes, run at stock speeds as suggested before and retry.

P.S.: When your system locks, does the display signal turn off after a time?
Stuttering sound or no sound at all when freezing?
What X1800XT model do you own exactly?

 

Hard crashes with ANY heavy load

Out of the blue, my computer has been crashing upon heavy loads. For example, playing a game. I can load into the menu fine, but when it finishes loading the game, either the game will crash or my computer will black screen and restart. Specs and what I have tried already are as follows:

• CPU: AMD Ryzen 5 5600G
  
• RAM: 32GB Corsair DDR4-3200MHz
  
• MOBO: ASUS X470 Prime Pro
  
• GPU: ZOTAC GTX-1070
  
• PSU: Corsair CX450
  

What I have tried:

• Updated drivers for CPU, GPU and MOBO BIOS updated
  
• reinstall GPU drivers via NVIDIA software utilities
  
• unplugged and reconnected all PSU connections, reseated GPU
  

I'm out of ideas. Any suggestions you have to fix my issues are greatly appreciated.