Troubleshooting a SQL Server with OS CPU and Processor Counters
The areas we need to look at are Process, Processor, System based counters:
Check the counters like
In Process
Process-%Processor Time < 80%
In Processor
Processor-%Processor Time < 30% of total % ProcessorTime
Processor %Processor Time < 80%
In System
System-Processor Queue Length < 4 per CPU
System-Context Switches/sec < 4 per CPU