I too have this problem. I have replaced the processor and the logic board and still get the same error. I have disconnected the display, hd, keyboard. Allways the same error. I also removed the RAM and the error changed to the no RAM present but resumed to the processor error when replaced. Could the optical drive cause this? I'm flummoxed.
Problem solved. A USB socket was damaged and causing a short circuit. I carefully removed the leads that were shorting and all is well.