The ECS motherboard is an ATX (Advanced Technology Extended) form factor. That means that the screw holes are arranged in a certain way and it is very popular among those of us who build our own computers. I don't know about the HP and that's where the rub is. I think HP and Compaq have a different form factor, as does Gateway. Unless HP is following a type of ATX form factor, the screw holes might not match. I'm not sure and I've been trying to find an answer online. If it's different, not all is lost, it may come in handy sometime.