That's a relative question. Power grid down locally, nationally, or globally? And for how long? None of the scenarios would make it worthless. It is technically already worthless. It is just numbers on a line with nothing to back it up. It is just a supply / demand pump that only has secure store and movement of value while demand remains. Only things not worthless are things you actually need to live. You also don't need computers, chips, phones, gold, silver. On the other hand, food, shelter, water, heat, security ...