Question Computer keeps turning off on it's own

[Tuk0]

My monitor and keyboard lights suddenly go black but my case fans and lights are still on. Happens randomly when gaming or browsing. Any ideas and what to do to diagnose the problem?

 

[rgd1101]

full system spec? include brand and model of the psu

 

[Tuk0]

full system spec? include brand and model of the psu

AMD Ryzen 5600 @ 4.2ghz cpu
RTX 2070Super gpu
T FORCE 2x16gb 3600mhz ram
B450M A-PRO MAX motherboard
EVGA 750 GA 80plus GOLD psu

Not overheating, have tried reseating gpu and bought a new one to fix the problem. Reattached connectors at psu side. Reseated everything. Still nothing. Sometimes it boots and sometimes it wont. Also randomly closes on its own. Motherboard issue?

 

[Tuk0]

Just got it to boot after a day and a half of troubleshooting. Anything i can do to diagnose the problem while the computer is still on? Before it inevitably shuts down and wont boot for days again 😭