New PC won’t stay on or show display

[llTheMaskll]

I’m building my Fiancée a new pc, all new parts. Everything is plugged in correctly and seated correctly, I go to turn it on and it does nothing, after some troubleshooting I found out it was the power supply, so I swapped it with an older PSU, and now it turns on but we get no display and then after a little bit it just shuts off on its own… Is this a RAM issue or a PSU issue or something else that I am missing?

[Allan B]

We need more details to help..

Full system specs, CPU, MB, RAM, GPU etc....

How long is it on for before it turns off?

If you wait does it turn itself back on after a bit?

[llTheMaskll]

CPU: I5- 14600kf 14 cores 

GPU: GeForce RTX 4060 

PSU: EVGA 650 gold 

motherboard: ASUS Prime B760- Plus

RAM: GSkill DDR5 
Right now it’s stayed on for about 8 minutes and still on but before it would be about 1-2 minutes and just shut off, it wouldn’t turn on by itself but I could turn it on manually again. Still no picture though. (EDIT: It has now shut off by itself after 11 minutes)