While troubleshooting a performance issue at one of my sites, I found we'd been maxing out an MX76 for a while causing all sorts of trouble.
The only place that let me know this was an issue was under Org > Summary Reports and then drilling down to that specific site and device.
I checked the alert settings, but didn't see anything for alerting on high CPU/device utilization. Is there some other way to get alerted to issues like this?