And you might even be able to track them down by measuring the power usage. 600 computers surely pull a measurable amount of electricity, so if you graph the power usage across the entire country and look for anomalies you might be able to spot when and where they come online.

It would depend how much noise is in the graph, and how much energy 600 computers use relative to the total energy usage of various parts of the grid. If they went to a major city, probably not. But perhaps the usage in a smaller town would show up as a spike.

I'm really curious whether this would work. Kind of a creepy thought. Hard to escape the eyes of modern technology.

On the other hand, they thought about every aspect of this heist, so maybe they're going to power the computers with gasoline generators. It's hard to know what to be paranoid about when thinking deviously.