Laptops are difficult to work on and have a lot of other issues; it's not like working on a desktop. Replacing the Celeron with a Pentium will probably cause overheating issues. If you mess with your laptop, all warranties are null and void. It's a small "enclosed" space and the manufacturer put in a Celeron for several reasons, not just because it was less expensive; there's all sorts of other parts that "want" the CPU to be a Celeron.