Or just get a new pc cos it sounds like a dead horse to me.
PSUs can blow up and take the motherboard with them, or might cause damage that weakens it and the fail comes down the line. Why are you so sure that the PSU has blown this time? Were there flames, smoke, smell or did it trip the mains?
Only real way to know for sure is check the components individually in a system known to work. Once a system has gone though its usually not worth fixing. A new one would be a better option.