I want to show my talent in programming and computer science to universities and i have already taken Math2 and Physics, as well as AP Computer Science, Calculus BC, and Physics C:Mechanics. What SAT2 should I take next?
More tests are not what you need. Look for ways to apply your knowledge. There is an inflection point with test scores in the US, where more =/= better.
If the schools you are applying to only required or recommend 2 and you have done well on them there is no need to take more. Spend the time on your essays and school work. If you need to take another to improve your scores, take what you think you can do well on and don’t think it needs to correlate to your intended major.
@WildChicken if your SAT subject test scores are good, then you’re done. There are better ways to pursue/show interest in CS (learning a new language or developing your own software, participating in CS competitions such as USACO, looking at difficult research problems in CS, etc.)