What does "bare motherboard" mean? no cpu or memory video card? If you have those 3 things attached why don't you have a keyboard attached? Need that to get into bios and maybe reset them. Unplug and remove the cmos battery, push power button for 5 sec. Replace cmos battery, plug back up and turn on. Most computers won't boot up unless there is a keyboard attached. That's one of the things the bios looks for during boot up.