(This is a copy of from another forum trying to figure all this out. I was told by Microsoft support to contact Manufactures.)
So to start off with, the PC is a New Build, Specs are :
CPU -AMD Ryzen 7 2700x 3.7GHZ
RAM -2 Sticks of 8g ddr4 3000mhz
GPU -EVGA RTX 2070 XC Ultra Super
PSU - Seasonic 750w Prime 80plus Titanium
MOBO-Asus Prime x470-PRO
CPU Cooler -DEEPCOOL Captain 240 EX
Case -Fractal Meshify C
 
TL;DR at bottom
 
After I first booted the PC and installed windows, I proceeded to install all the updates I could think of. I updated Windows till I couldn't update any longer. I downloaded the newest Graphics drivers, then I found the news BIOS version and flashed the BIOS. After all that, I started to install games. The first one I got to play was Borderlands 3 (Which I have read that many ppl have optimization problems with, but this goes beyond one game). I got to play for about 20-30 minutes, then the game crashed. I proceeded to reboot the game and it followed with even shorted times between crashes till it finally rebooted my PC. I then, after a time to allow my time to cry(PC to cool), installed No Man's Sky to see if it was the game or my system. I got the same results. I then did some research. Which had me download some programs.
 
I installed Core Temp, and EVGA Presision x1 and started monitoring my CPU and GPU temps. Highest CPU Temp I have seen was 51c. Highest GPU temp I saw was 81c. I continued to monitor these thinking it had to be a heat issue. I stopped booting BL3 as the game crashes in seconds now. I instead tried NMS. I got a good 5 minutes of solid play, and noticed the CPU temps stayed in the mid 40s and the GPU temp between 60-70. The GPU memory was around 7k MHz. The GPU clock was showing 1900 MHz. It then crashed and gave me a generic error telling me to visit their site. I spent the next 30 minutes trying to figure out the problem was, and tried one last game.
 
I tried a less resource heavy game, WoW Classic. I didn't see a difference in temps nor usage, yet I was greeted by a reboot. I have no idea if its a heat problem, bad hardware, faulty software, or a power issue. The PCI-E cable I have to my GPU is a 6pin and 8pin(6+2). The install manual was showing me a input cable that I didnt have(Something to do with the 8 pin having a barn looking hexagon on top of another hexagon on the +2 part, but I only have cable that are square on top of hexagon) , so I used one of the 5 PCI-E cable my PSU gave me.
 
So I have no idea if that could be it. If you couldn't tell by my explanation of PCI-E cables there at the end, I am not that knowledgeable about these things.
 

TL;DR- PC crashes/ Reboots. Have newest Graphic drivers, Windows updates, and BIOS updates. Thinking its heating issue. Have monitored temps and from my knowledge, and they are in acceptable range.
 
ADDED: I now have had my first crash while not gaming. Also I read someone's comment on another post about resetting gpu and RAM. So while doing so, I took my cooler off my cpu to see what the factor paste looked like and saw what looked like a electrical arc of sorts, like current trying to cross between two points. Also the paste on my CPU looked a bit dry and cracked. This doesn't seem healthy.
 
Thank you for any assistance you may lend

Just a couple things.
Are you overclocking the GPU/CPU? 
Test it with everything set to stock?
Is the memory speed and timings set to auto or manually set?
How about all the voltages for the memory and CPU, auto or manually set?
Double check manual and ram sticks are in the proper slots?
Double check all the wire connection plugs are fully seated.
Using two separate wires from PSu to the GPu and not just one wire with dual ends?
 

Last night I actually did just that. Unplugged everything from PSU and plugged it back in. re seated the GPU and and RAM. I then did a clean boot and installed Win 10 again. updated till I coudn't any more and got the latest drivers. I downloaded Steam and installed Witcher 3 to try and see if anything changed. I didn't have a crash, so I closed the game and went to see if any of my forum posts updated. While doing so the screen went black and I was greeted with a reboot. It happened twice within 5 minutes. After posted on a few other forums I installed No Man's Sky again and was just play it for  about 30 minutes. Temps were good and no crash. I never saw the CPU temp over 51, but Core temp says the highest it saw was 60. GPU stood around mid 50s. I am still skeptical though due to random crash with no load on the system, followed by another shortly after. 
 
AS for overclocking, I haven't even touched those systems. everything is set to stock and auto. Memory are in primary slots 1 and 3. I will have to recheck and get back to you on the psu to gpu wire. not 100% if its a split or two. 

Snowman5728
Could I instead insert my old GTX 970 and see if there are any problems there?

You could, but the 970 uses less power than the 2070s. 145w vs 215w.