Question PC is randomly crashing and restarting

[ZupDup42]

Hello,
I have a PC I built during COVID: (6800XT, 5600X, 16gb ddr4 3600), which I have been having several errors that have been increasingly occurring now.

There are 3 main issues:
1. My PC was originally shutting down, however has since been solved, (re-seating the CPU and new thermal paste).
2. The PC randomly shuts down, with no error or BSOD, or even a message saying overheating issue. This happens at any time, can happen 2 times in a row and in any games too.
3. Occasionally when I turn on the PC it will be distorted and discolored (Included Pictures). I have used several different Display port cables. Not sure if it is my monitor as I cant get it to repeat itself, it just happens randomly. It is always fixed by disconnecting power and display cord for 10 seconds.

I am wondering if these issues are related? Anyone know what it could be?
Thanks.
Pictures

 

[Lutfij]

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
include the age of the PSU apart from it's make and model. BIOS version for your motherboard?