The danger from CMEs comes from very very large scale current loops (thousands of miles in perimeter, hundreds of square miles in enclosed area). The issue is

The danger from CMEs comes from very very large scale current loops (thousands of miles in perimeter, hundreds of square miles in enclosed area). The issue is a slowly varying but intense change in magnetic flux. We're not talking even as strong as the earth's magnetic field, but over a large encircled area you can get one hell of an EMF. This is bad for power lines. This can also be bad for thousand foot tall AM radio towers and their conductive guywires. This is not a problem for your cell phone. Your hard drive, even if it is legacy spinning metal in a live laptop disconnected from your wall power will not notice any more than it will notice you setting your credit card down on the palm rest, from some basic order of magnitude on the change in dB/dt.