The HP ProLiant DL580 G4 now supports Dual Core processors with an 800 MHz Front Side Bus (FSB).
HPE ProLiant DL580 G4 Intel® Xeon® 7030 Dual Core Processor 2.80 GHz 2MB 4GB 2P SAP400 Rack Server
HPE ProLiant DL580 G4 Intel® Xeon® 7030 Dual Core Processor 2.80 GHz 2MB 4GB 2P SAP400 Rack Server