After I plug-in the Parallella board, it responds just fine over SSH for awhile. But if I come back an hour later, the SSH connection has been dropped, and I cannot reconnect. During this time, I don't have any programs running on the board, so it should not be overheating. My board came with the giant heat sink and made sure the thermal tape was properly placed on both the Zynq and Epiphany chips.
I have not connected a serial cable yet to see if any traces are coming across before it becomes unresponsive. I just wrote a program that sits in a loop for several hours running ztemp.sh and appending the output to a log file, to see if the temperature is creeping up over time. If the program runs all night then I guess that might support my hypothesis that the board is going into some sort of hibernate or sleep, because the program would prevent that from happening, and if it is overheating, then I should see it in the log file as it creeps up to the point where the watchdog takes action to save the board.
My question is, does Parabuntu go into a low power state if it is idle? Is there some sort of wake on LAN type of thing you can do to remotely knock it out of this state?