Have to exchange it bought original fan of Synology DS212j me this fan. This is unfortunately quite noisy and produces an unpleasant humming or clacking. The DS is a bit picky with regard to the selection of the fan, otherwise there will be error messages. The Arctic F9 but is the ideal replacement fan for the DS! Fits 1: 1 in the case, does not cause any error messages and is completely inaudible! And the price is also very cheap!