I am in the process of rebuilding our SCCM environment from scratch at the University after initial setup from previous guy had several issues in how it was configured and he broke after installing SCOM in the incorrect order. We are currently running SCCM 2012 on Server 2008 with a local SQL database and going to server 2012 R2 with SCCM 2012 R2 and migrating database to an instance on our enterprise system. Still being new to this and knowing the powers of SCCM, what is the proper way to decommission the old server and bring the new server online without issues to the 2000 clients? Best to set up separate instance and migrate clients or to take down and migrate site information and keys? Right now we only use for Endpoint Protection and imaging with plans on rebuilding the imaging process and driver database from scratch. Any detail or input would be greatly appreciated.