The HP ProLiant DL580 G4 now supports Dual Core processors with an 800 MHz Front Side Bus (FSB).
HPE ProLiant DL580 G4 Intel® Xeon® 7140M Dual Core Processor 16MB 4GB 2P SAP400 High Performance Rack Server
HPE ProLiant DL580 G4 Intel® Xeon® 7140M Dual Core Processor 16MB 4GB 2P SAP400 High Performance Rack Server