Please use phrases in an example sentence. Often times I hear the phrase "so much as" used in sentences like...He didn't give me so much as a wink to his intentions.
The other phrase is used in sentences like...So much for diplomacy. or, So much for political correctness. The phrase is used to convey futility.
The first phrase is also used to convey frustration, futility, but they are used in different sentence formats. You have not included so much as crumb of information on why you want to know this. So much for responding to threads!