Are you’re running System Center Configuration Manager 2012 SP1 and you need to now support Windows 8.1 and Server 2012 R2 clients? Or, do you want to utilize new Server 2012 R2 machines as Configuration Manager site systems? You’ll need to download and install SCCM 2012 SP1 Cumulative Update 3.
Here is an example of what a Server 2012 R2 client will appear like in the System Center Admin Console if you attempt to manage it:
For more information about CU3 check out this blog post from Microsoft: