The NH-D15 G2 comes with two different fans (PPA/PPB), where should I install which?

We recommend installing the 1475rpm PPA fan in the centre (between the fin stacks) and the 1525rpm PPB fan on the front fin stack for optimal acoustics.

If you would like to achieve an even smoother sound signature, please consider further reducing the speed of the PPA fan, as described in this article.