You can start by trying the HP support web site and entering in your model number to bring uo the spec's of your laptop. If HP doesn't give your the info that your looking for you may not find it because the big computer makers have parts special made for them. This can happen because they will order such large amounts that they can get a motherboard made to thier specifications and it's one that won't be for sale to the general public.
You can try two ways , the motherboard and the hard drive. The sataersion of the hard drive may tell you what the motherboard is.