Windows Server 2008 R2 introduces new and revised performance and reliability monitoring tools intended to help network administrators better understand the health and operations of Windows Server 2008 R2 systems. Just like with the Group Policy Management Console, the new Reliability and Performance Monitor shows up as a feature in the Server Manager console. By clicking on the Performance Diagnostic Console, the tool shows up in the right pane.
The new tool keeps track of system activity and resource usage and displays key counters and system status on screen. The Reliability Monitor diagnoses potential causes of server instability by noting the last time a server was rebooted, what patches or updates were applied, and chronologically when services have failed on the system so that system faults can potentially be traced back to specific system updates or changes that occurred prior to the problem.
By combining what used to be three to four tools into a single console, administrators are able to look at system performance, operational tasks, and historical event information in their analysis of a server problem or system operations instability.
Source of Information : Sams - Windows Server 2008 R2 Unleashed