Help Needed: My PC Crashes Irregularly During Games

I bought this PC from a German manufacturer, Dubaro, earlier this year during a promotional sale that made it cheaper than building one myself. Here are the main components I have:

- Endorfy ARX 700 case without RGB
- MSI MAG A850GL 850W ATX power supply
- MSI B650 GAMING PLUS WIFI motherboard
- AMD Ryzen 7 7800X3D processor
- Endorfy Fortis 5 cooler with thermal paste
- Kingston 32GB DDR5 RAM (5600 MT/s)
- Lexar 2TB NVMe SSD
- Powercolor RX 7900XTX graphics card

I also have an external Kingston SSD connected, but it's not frequently used.

The problems I'm experiencing are quite frustrating:

- **Case 1:** The game I play (mostly GTA Online) crashes unexpectedly—first, the image freezes, then the game window closes with an error from the game, followed by a driver timeout message from Adrenalin.
- **Case 2:** In some instances, everything freezes, including my desktop, requiring a hard reboot. This happens infrequently but usually follows Case 1. The crashes occur irregularly—some weeks have no issues, while others have multiple crashes.

I've already tried several fixes:
- Disabled all overclocking settings.
- Reinstalled GPU drivers in various versions.
- Sent my PC to Dubaro for testing; they found an SSD issue and replaced it, leading to a full Windows reinstallation.
- They've suggested it might be my RAM since it's not on the QVL, and I reduced the speed to 5600 MT/s at their advice.

Despite all these efforts, the crashes persist. I'm open to any additional suggestions or information that could help!