You should try to narrow down what could be failing before declaring it dead. Beeping can mean a lot of things.
Reset the CMOS
Unhook all unnecessary devices (hdd, addon cards)
Reseat all of the power connectors (8 pin and 24 pin)
Swap in known working RAM or try one stick at a time, in different slots - one might be broken
If you have another power supply, try that in its place
If it has an external video card, try another one
Remove the motherboard and run it on a non-conductive/non-capacitive surface (i.e. do not run on anti-static bags)
Give it a careful inspection, making sure it is clean and there are no scorch marks