Windows 10: Why does my PC keep randomly rebooting?

So I built a new gaming rig, but every time I open a game, it will run for a bit then randomly restart the entire pc. meaning it shuts off and then is immediately back on. I don't have a hardware issue because I swapped components out and it still did the same thing. I even tried to look at Event Viewer to see if there were any errors or critical errors, but all I found was the error of my PC shutting off unexpectedly. The game I was playing is called Minecraft Java, now you may say that my components were overheating but I have a good cooler in my pc and both CPU and GPU were operating at 4

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PC Randomly Reboots

Just recently, my PC started to randomly reboot, to start it was once every other day, and know every few minutes.
Any suggestions to rectify this problem would be greatly appreciated.

 

PC reboots (no BSOD) on CPU stress

Hi fellow TPU members,

not too long ago, the box my gf's PC was transported in gave way on the stairs. Yes, you got it right, that sent a PC tumbling down a flight of steps alright.

Stuff broke. Also, stuff remained intact somehow.

I bought her a new case, new CPU cooler and we removed the floppy drive, so far so good. But the PC started crashing for no apparent reason, without a BSOD.

I tested:

• Memtest86+, left overnight, 0 errors
• Scanned the HDD for errors, nothing there
• Left FurMark burning up the GFX card and drawing some power, no problems there
• Ran Ubuntu from a Live CD doing nothing special, didn't crash
• Ran OCCT, Linpack, Prime95, all 3 caused reboots within minutes
• Oh, and I disabled "Restart on error" so I'm sure it's not a BSOD.

Now, I can still try and test something CPU intensive on Ubuntu, but my guess is the CPU didn't survive.
Before I do anything drastic like whippin' out the magic wallet and get her a new AMD quad, is there anything I didn't see?
I'm guessing the motherboard could be borkered as well, but can I check that other than replacing the CPU with a working one?
Any suggestions on which proggies I can use from an Ubuntu Live CD to stress the CPU?

 

PC Randomly Rebooting. Not Temps!

My PC randomly reboots when I play a demanding game, its not the temps as they were 40 CPU and 60 GPU when it rebooted. It started hapening when I updated to W10, all drivers are up to date. Help?