Can CPU usage be monitored in Event Viewer? I don't want to use a third-party software. Can I set a rule so that Event Viewer can show me if the CPU usage gets higher than a set value?
In Event Viewer? No, that only shows events. You can however use the Performance MMC snap-in. Run
You can also configure it to log an event to the Application system log by adding and configuring an alert.
1) You can explore the possibilities of the command line eventcreate.exe in system32...
2) Follow the advice of Synetech
Here's a short How To from MSDN Blog: How To: Use Perfmon in Windows 7
The files for your Performances collector for the CPU will be save in C:\PerfLogs
But this is not a complete answer to your question since, as far as I know, the perfmon use built-in performances counters and not a user created counters such as a «CPU usage gets higher than a set value» (This must be verified!)