I know the rules about linking to other boxing sites on here are a little strange, but if you google "Mayweather kd marquez" the first link has a few clips of it. It's a solid punch, but not thrown with nearly the mean intentions of the punch that Pac hits Hatton with.
Floyd isn't a power puncher and doesn't try to be. That said, he has power enough that it should be respected by his opponent. If someone tries to rush through Floyd, he'll find himself eating hard enough counters to make him rethink that strategy. It wouldn't surprise me to see Pacquiao get caught cleanly with a hard counter and ultimately stopped. Floyd is a good finisher when he has a man hurt.
Floyd's power is somewhat under rated here. The reason for the fewer KOs later in his career is due to him really choosing his shots.
i htink he has good power he isnt a feather puncher, he did not only knock marquez down but hurt him, and marquez can take a punch but if u compare to mannys power then ya i guess u might be able to say mayweather has no power. The thing is manny throws the power shots and tries to knock u out mayweather doesnt he just stings u confuses you outpoints you never really looks like he is trying to knock u out so maybe if he actually threw to KO he might have more knockouts?
he's got good power. not great, but he's got more than enough to get respect and put you on your ass if need be.