Question New build suddenly restarted under heavy graphics loads.

Jul 24, 2020
New build suddenly started restarted under heavy graphics loads that it handled fine the day before.

I have a build that's only a few months old. Specs are as follows...
msi B450 Gaming Plus Max​
Ryzen 5 3600​
EVGA 700w ATX12v/EPS12v 80 Plus Bronze PSU​
Radeon RX 5700xt​
g.skill ripjaws v 16gb​

The day before yesterday, everything was going fine. I was playing Sea of Thieves much of the day, then spent a few hours watching twitch. Then the next day (yesterday) I watched some youtube on firefox before going to play more SoT, but about ten or so minutes in, the pc spontaneously restarted. I tried again and got about 15-20 minutes in before it restarted again. So I looked into the events, but I'm not computer-savvy enough to figure out what the problem is, and googling has been no help. I understand that the PSU is the most likely culprit, but I can't imagine it is as it's the newest component of the pc (I decided to upgrade from a 600w). Today I did some benchmarking with Heaven and saved all the events as well as Afterburner's readouts leading up to the crash.
Hardware Monitoring
I've had so much trouble with this pc, I'm completely burned out on trying to get it to work properly. First a DOA motherboard, then a CPU that randomly died and had me getting a whole new ssd and PSU trying to figure out what was wrong. I've never overclocked or messed with bios settings or anything. I updated all the drivers just a week ago when I had to reinstall windows after getting a new CPU. Now I'm eyeing the GPU as the culprit, or even the wall socket I have the surge protector plugged into (there was a storm when the first restart happened, but the electricity hadn't gone out and there wasn't much lightning) but due to a short ethernet cable I can't easily move to another socket until monday when the longer one I bought comes in. If anyone can interpret this data I would be so grateful. The temps all seemed within reasonable degrees, but I'm not sure if GPU usage should be so high? I hadn't benchmarked before the issue, but I was keeping a close eye on the temps and performance with HWMonitor, GPU-Z, and the Radeon software, and saw no issues even after hours of gameplay. I just have no idea what's going on at this point and I'm beyond exasperated.
May 11, 2020
This sounds very familiar to what my friend just went through. After frying his first new PC after 6 months with a space heater. He built a brand new PC instead of getting another pre-built. Basically has the same specs as you. Everything seemed fine for a month than he started getting random restarts. Almost always is a game. Many people including geek squad tried to diagnosed his PC but couldn't. After a month of hell for him. it was determined that the power supply was bad and causing the problems. It wasn't even passed the store warranty so he got to swap it out on the spot and has been problem free since.

This happened this year in 2020 so i wouldn't put it past a quality problem with the power supplies. There was a big shortage and wouldn't put it past a company to cut some corners or try new untested suppliers in the new economic environment.

If its only a few months old go back and swap out a power supply. Store don't generally test if they are bad cause its nearly impossible to do so.