Now there's official confirmation from AMD that they've identified the root cause and that a BIOS update is on the way. Here's the message AMD provided to German tech site Heise:
"We are aware of select instances where FMA code can result in a system hang. We have identified the root cause and will soon release BIOS updates to motherboard vendors that will resolve the issue. Please watch for new BIOS updates from your motherboard vendor to incorporate these changes."