I heard from Gigabyte tech support and had to go into more detail on the problem. They had a hard time with the apparent 31-day cycle of the non-start event. This has pretty much baffled everyone. I held off updating the BIOS until I could hear from them and will wait another day or two. There is no urgency here, knowing how to get the machine back. If it hasn't been solved by the beginning of August, I am going to try simply unplugging for a few minutes before what I have been doing.
I will post again when I hear back from Gigabyte.
I thank EB-1 and others for the insight offered. Some of my concerns with incompatibility have been lessened.
