Sometime I can start up OK, other it won't start at all & just get this continuous beeping noise. Other times it just cuts out during start up and starts beeping at me. Could be related to a display problem I'm having with colour flickering on and off on the monitor. One minute it's green, then blue, red, black before going back to normal colour. Nothing reported in device manager as not working properly.
The beeping is beep codes to tell you whats wrong click here it depends on the make of your BIOS it will tell you when it starts up AWARD BIOS or AMI BIOS or whatever. Find out which you have, listen for the beeps and check them against the list.