We have Oracle 10g (64 bit) 10.2.0.5 on Windows Server 2008 Enterprise SP2, and we are planning to migrate our geodatabase from 9.3.1 to 10.3. 

As per Esri ["Oracle database requirements for ArcGIS 10.3.x][1]" the maximim OS is SP1. 

Does anyone know what is limitation/risk/impacts if we keep our OS SP2 not SP1 and migrate our geodatabase? 

  [1]: https://desktop.arcgis.com/en/desktop/latest/get-started/system-requirements/database-requirements-oracle.htm

And what if we migrate our ArcGIS Server/Desktop to 10.3 and kept using geodatabase 9.3.1?