Hey you! Have got hold of an early 2009 Mac Pro does not start anymore and I'm in doubt about what to do with it. Diagnostic lights on the motherboard flashes on CPU A and B, so when I put in a CPU board from a similar machine it starts up just fine. I have read that there isn't a big problem for a technically astute person to switch CPUs, but wonder if there is a chance that it is the CPU board and not the CPUs that are broken given it says both are dead. My questions are: 1) Can it be only the CPU boards that are broken? 2) Is it worth buying new CPUs, possibly new CPU board to try to get this machine up again? 3) Where do I find the best guide for switching the CPUs?