Computer power resets during some games

[AndrewWiggins]

I'm having a major issue with my system.  This was a pre-built from ibuypower (through Costco), my previous workstation died and I needed something that day as I work from home.  The system has never been overclocked or under-volted.

 

Specs:

• Intel i7-9700k @ 3.6GHz
• ASRock Z390 Phantom Gaming 4-IB (custom ibuypower BIOS - latest from what I can tell)
• Apacer 32GB Memory DDR4-2666 (1333 Mhz)
• NVIDIA GeForce RTX 2080 8GB (powered)
• Came with a WD Green 512GB SSD ( died, warranty upgraded to Blue 1GB )
• Added another WD Blue 1GB SSD
• Added external USB3 (external power) - 6TB WD Blue
• Added two external USB2 WD 10GB easystore ... for back up only
• [ I don't have the power rating of the power supply ]
• Everything is on a APCC 1500 UPS

It's a very odd situation, in some games there is no issue in some games it happens 100% of the time and the graphic settings don't seem to make a difference.  The length of the session does not seem to matter either.  Sometimes it's within 10 minutes of game start, sometimes an hour later.

• Diablo 3 - I don't recall it ever happening
• World of Warships (Settings don't matter) - every once in a while
• Astroneer (low poly game, max graphics) - almost 100% of the time.
• Cities Skylines - almost 100% of the time (settings don't matter, size of city doesn't matter)

I have tried using bleed edge display drivers, studio drivers, drivers from months ago (a specific one a GeForce rep on a forum recommended for maximum stability). 

 

I'm at a loss on where to even begin diagnosing this.  I don't have any parts to swap them to narrow down the issue.

[Parideboy]

If the pc just restarts by itself it's probably the PSU. Try lowering the powerlimit of both gpu and cpu and see if the issue still occurs