I am not sure if we actually have the POST sequence described in a flow chart version. I do know that the POST sequence occurs in the order is listed in the Diagnostic LED POST Code Decoder.
You have covered most of the troubleshooting steps that I can think of (minimum configuration, BIOS bank selection, different processors, and tested the memory).
Have you inspected the socket pins? I would also consider removing the board from the chassis to eliminate a possible grounding related issue.