No Power to PC

When your pc starts to boot up do you get two beeps one then another, although not two together, if not and only one beep occurs
this could mean a memory problem, two beeps together normally a cmos bios problem.(Only part you've not changed was your ram)

Do you get as far as the bios screen?, if so look for a line in advanced cmos settings, saying 'halt on all errors' dissable this and sometimes on boot up the problem will show itself in the initial dos screen.

Keep diggin.

i think only 5 v in the power supply is working the 12 v supplu thats the yellow wire in psuis not workin and the orange wire 5 v is also not working check ur psu shorting the green and rthe black if the psu is working then the power supply is ok either the supply has been shorting to chaisis