It is possible that it is a mainboard failure if the cpu was bad what caused it to fail,there could be a damaged component on the board maybe a voltage regulator or one of the chipsets has gone bad,as for a bad bios it is possible, do you know the history of the board let me know and i will try and help as much as i can,this is the link to the service manual.
http://h20000.www2.hp.com/bizsupport...Fc01122313.pdf