There must be a 300W Power/Cooling Module (PCM) for everytwo adjacent boards in the system, because the fans inside the PCM are the only cooling for those boards. This means that if a board is added to the system, there must be an associated PCM. If one ist not present, it must be added.
Each Power/Cooling Module (PCM) supplies enough power for two boards, although in a fully loaded configuration one supply can be lost and there will still be enough power for the remaining board (N+1).
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