What is HP iLO ??
HP Integrated Lights-Out (iLO) is one of the bright feature available on all HP Proliant and Blade Servers (hope you are not using Antique HP/Compaq Servers). iLO allow us to manage server remotely and it works at the hardware level. So you will have access to the server even when the Operating system is crashed/not installed/Server is in Powered Off state! -
See following link for more info