I have multiple instances of SQL 2012 Std Edition on a 40 physical core server.
What I have done is the use the Process - SQLServr -% Processor time Stat and divided by 16 ( the max number of Cores Std ed. can use) as a instance level measure. I also use processor object stats to show how busy the server is.
Does anyone have any other suggestions on how to represent the servers CPU utilization?