A 84
Not officially, no. Well, I mean, you can always strike for nonlethal damage by taking a -4 penalty to your attack rolls, but otherwise there's nothing that lets you just deal less damage.
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It's not RAW, but I would normally suggest a house-rule that allows someone to reduce or remove their Strength bonus to damage rolls (to a minimum of zero) for these types of situations. Honestly, I'd really recommend just using the nonlethal attack rules, since trying to hit somebody for lethal damage but going for as little damage as possible is an extremely fine line to try to walk. Easier to just try to knock them out in lieu of killing them, IMO. But, again, that's a little beyond the scope of this thread.