Windows 10: Crashing [shuts down] under full 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:- 15 to 30 mins into heavy gaming load - Or if I ran the Prime95 and Superposition Benchmarks simultaneously, pushing CPU+RAM+GPU to 99-100%. Several minutes later, it crashed again in the same way when I game. If I run them alone, no issues. 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

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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?

 

win 10 upgrade crashes computer and will not load windows

PC Win7 64 bit. I tried to do Win 10 upgrade and not save files or apps. PC crashed during upgrade. I tried all the steps listed. It would not let me load image disks that I had made or the system repair disk. I tried to restore to factory setting.
That didn't work. Now the computer tries to load windows but its tells me the computer was shut down improperly and restarts with the same message. It will not start in save mode.