|I don't understand what that means.|
Are you saying you replaced the PSU for one that has a power outlet that your monitor connects to instead of the monitor connecting to a wall outlet or other powerstrip?
So there was basically nothing wrong with the PC until you opened the case to remove the old working PSU?
Have you tried putting the old PSU back in to see if the system will still boot?
Goin' Fishin' (Some day)