The May 2011 (and later) revisions of the System ROM for the HP ProLiant G2, G5, and G6-series servers listed in the Scope section of the support document include enhancements to the System ROM flash update process. These enhancements improve the reliability and security of System ROM updates by reducing the possibility of unexpected corruption of the flash part.
Because these enhancements require modifications to both the System ROM and the flash update utility, the May 2011 (or later) System ROM cannot be downgraded using the flash components available on the HP Support site that are dated earlier than May 2011.
However, the System ROM can be downgraded by creating a new flash component using an older System ROM revision. For more information on how to downgrade the System ROM, see the HP Support website at http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?locale=en_US&objectID=c02838375.