Hp Compaq Dc5800 Small Form Factor Bios Update ((exclusive)) Online

Updates allow the motherboard to recognize newer CPUs (like the Core 2 Duo E8400) and memory modules.

Open CMD as Administrator and type: wmic bios get smbiosbiosversion hp compaq dc5800 small form factor bios update

Before you attempt an update, you need to know what you are starting with. Updates allow the motherboard to recognize newer CPUs