I just asked a question about PCA and scipy's implementation of PCA compared to mine. You can find it here:
It seems the question could have been very suited for this site. How do I know if this question specifically was better for stats.overflow, stackoverflow or computation science overflow.
It depends on the question you are trying to ask. If your question is an algorithms question, Stats or SciComp would be good fits. If you want a statistics perspective on PCA, ask Stats. If you want a more general computational science perspective on PCA, ask SciComp. Sometimes, SciComp users are also willing to help with debugging; I am not sure about Stats, since I don't spend much time there.
StackOverflow, as far as I can tell, is mostly about programming. There are people who answer math questions over there, but the site isn't devoted to math algorithms; it's devoted to programming and software development. So if you want a programming or software development perspective on PCA, ask StackOverflow.
