In above cases, the first is the most plausible and probably most up to date / modern. The second one lacks content in the first part of the sentence to allow for the comma to only be placed before 'however', but I get the idea.
I do reckon the confusion with 'however' is due to its many usages.
If 'however' indicates that the relationship between two independent clauses is one of contrast/opposition (used as a conjunctive adverb to make a compound sentence) - a semi-colon is to be used before and a comma after it. (Something I actually didn't know, semi-colons is not something I see often used.)
However, if you start a sentence with 'however' it must be immediately followed by a comma and a complete sentence thereafter (regular and probably easiest use of the word).
Using it as an aside allows for a comma both before and after the word - at least, that's what I keep encountering on the internet. http://www.sonoma.edu/users/f/farahm...es/however.pdf (not the only source I used)
Of course, you can also use it in the context 'by whatever means' (see source) - in which case neither comma nor semi-colon is required. E.g.: "However much chocolate I gave LadyIntegra, she was never satisfied."
I can conclude that it's better to avoid the word entirely when it's not fully clear, and just reform the sentence instead, heh.
Wow - I feel educated again. I'll never be able to read a sentence with 'however' in it as I did before.