reply to daveinpoway
Re: Supermicro motherboard beeping I finally got ahold of the Supermicro support people. The man I talked with said that the beeps indicate local overheating, but he had no explanation as to why unplugging the rear case fan (which, if anything, would cause the internal case temperatures to rise even higher) will make the beeping stop. He also said that I should add a front case fan, but, again, he could not explain why the system has been able to operate for over a year with no front fan without beeping. Since the system is basically loafing (the AC power consumption is only about 40W), adding a front fan would not seem to be needed. As it is, the air blowing out from the rear of the case is barely warmer than the room temperature.
He did have a good suggestion that I should try plugging the rear case fan into a different connector on the motherboard (there are 2 unused fan connectors). If/when the beeping starts again, I will try that. It will help determine whether there is an electronic problem related to the connector I have been using.