First of all try resetting your BIOS. Instructions in your motherboard manual will tell you how to do this. But generally it involves moving a jumper on the motherboard
take all your cards out (sound, modem, network etc except graphics)
disconnect all drives from the motherboard
Try booting now, if it boots put it all back in one by one until you find the faulty component.
If it doesn't then your'e only left with motherboard,chip, memory and graphics card.
If you have more than 1 dimm, remove one and try again, if that doesn't work, try the other.
If it still doesn't work really provoke it by leaving the memory out altogether, it should beep plaintively, this would prove the motherboard and chip works.
If this still doesn't work, put the memory back in and try taking the graphics card out, if it beeps now then it the grahics card faulty.
If it still doesn't boot, then your'e just left with chip and board.
Only way to test these is with another working processor. put the working one in and if it boots then it;s the chip, if it doesn't its the board.