Windows Server 2012 - Resource Monitor
Resource Monitor is a great tool to identify which program/service is using resources like program, applications, network connection and memory usages.
To open Resource Monitor, go to Server Manage → Tools.
Click on “Resource Monitor”, the First Section is “Overview”. It tells how much CPU is consuming every application and on the right side of the table, it monitors in real time the chart of CPU usage. The Memory tells how much memory every application is consuming and in the right side of the table it is being monitored in real time in the chart of CPU usage.
The Disk tab splits it by the different hard drives. This will show the current Disk I/O and will show the disk usage per process. The network tab will show the processes and their network bytes sent and received. It will also show the current TCP connections and what ports are currently listening, IDs too.