According to The statistical nature of the 2nd Law of Thermodynamics, the second law of thermodynamics probably hasn't been proven to be absolute. That doesn't necessarily mean it hasn't been proven that a perpetual motion machine of the second kind is impossible. It follows from the second law of thermodynamics that it's impossible but does not follow the other way.
The question Perpetual motion machine of the second kind possible in nano technology? doesn't have an answer that I think satisfactorialy answers this question. I think this answer could be wrong because the second law of thermodynamics probably hasn't been proven to be absolute. Some of its other answers probably satisfactorily answer that question but not this one.