First, a brief history lesson. Pegatron is an original design manufacturer (ODM). They build motherboards for HP, Dell, and Apple. When you buy an HP desktop, the motherboard inside is rarely labeled "HP." Instead, it carries the ODM's model number—in this case, .
Locate the CLEAR_PW jumper. Move it to pins 1-2 for approximately 10 seconds, then return it to pins 2-3 to remove forgotten BIOS passwords. pegatron motherboard m2n78-la manual