yuck that sounds awful
On an off topic I too agree that the AMD fans are becoming quite annoying not posting any helpful advice with the Intel based threads...If your not gonna help just dont post.
Back on track.. What I woud like you to so is pin point the problem. Unplug EVERYTHING except the P4 power plug, the main MOBO power plug, and the CPU heatsink/fan power plug..and of course leave your power/reset button etc etc plugged in. However if it still makes the noise then unhook all other non-needed wires except the POWER SWITCH wire(unplug reset button, speaker, HDD light etc). If it still does it with the bare minimum then it is either the chip/mobo.
Again for this test you want the bare minmum you need for the computer to turn on..remove RAM, VIDEO CARD, PCI CARDS, ALL DRIVE POWER AND IDE CABLES etc...then if it works plug in one thing at a time until you recieve the error then you know what it is.