|If you get no beep at startup, it's one of 3 things....the board, the CPU or the power supply. You obviously jumped the gun by buying a new board (especially since it didn't fix the problem) but at least it rules out one of the 3.|
We need to know the specs of your old power supply & the one you replaced it with. Not just the wattage, but also the amperage specs for the +3.3v, +5v & +12v rails. Brand name would be helpful too.
When you test the system, make sure you disconnect everything. That means no drives (HDD, optical or floppy), no cards (sound, video network, etc), & no external devices (mouse, speakers, printers, USB devices, etc) except the keyboard...keyboard should be PS/2, not USB. Connect the monitor to the onboard video & if you have more than one stick of RAM, remove all but one. Now try to boot. If it still doesn't boot, remove the remaining stick of RAM & try to boot again...the board should beep like mad. You do have an internal case speaker connected, right?