Basicly take anything off that you can sell for better price than the board it self (low grade boards only) any other grade of board you'll degrade the board. Also don't take anything off a power board, a good example of power board would be the boards from power suplies. I take aluminum off and I clean it, it's easy and quick, I take large copper windings and IC chips. I leave transformers on becuase I get more for the boards than I do for transformers.