It would be a good idea to post a signature with all of your equipment listed. It could be you are a little short on power, what is the voltage on the 12 volt rails of your power supply?
The Psu is an antec 380W
These are the readings
for the 12v rail its 24A if thats what you needed
The beeps may well have been down to the fancy case, a bog standard case gives me NO BEEPS
If I keep in the memory, video card and cpu with HSF the system shuts down after around 15 secs
If I take out the memory and remove CPU the system stays on but no beeps, no boot