Question Help regarding Pc shutting down randomly

[Rs20201]

Hello, my computer seems to be shutting down randomly. No warning, no specific screen when shutting down. It may last hours then will shut down after not using it for days(leaving it plugged in) then when i try putting on straight after it shuts down, it starts then after a few seconds it dies again. I have replaced the power supply and the same thing continued happening. Can anyone help? Also, i do have a video i can show you if you would like to see, but not too sure on how to link it to this thread, just let me know and ill give you my instagram.
Many thanks.

 

[rgd1101]

full system spec? include make and model of the psu

 

[Ralston18]

Update your post to include full system hardware specs and OS.

Include PSUs - both original and replacement.