Question Pc goes on for a few seconds then dies

[Zoo-Boss]

Hello everyone hope you are doing well
So i have a kinda old pc to repear and here is the thing , When they brought it to me the pc didn't start i thought it was the PSU so i bought a new one
I connect the new PSU and here is what happened, when i plugged all the cables in it went on for like 3 seconds and then died. The thing is that when i don't connect the 4pin connector the power stays on. What can i do to solve it?

 

[Grobe]

Please list up full hw speccs.

Also get a description on how it died (dropped into floor, attemt to upgrade, etc . . ) in the first place.