Noctua has released its NH-D15S to stand alongside its NH-D15. The NH-D15 is a huge heatsink, a full 15cm wide. The NH-D15S looks like the D15’s twin, also 15cm wide. Where do the two differ? The NH-D15S is moved over to make more room for the first PCIe slot, and it comes with one fan, not two - this keeps the price down. Otherwise they are the same heatsink. Think of the NH-D15S as the high-compatibility version of this heatsink. The single fan configuration gets you a highly capable dual tower cooler with very good RAM and PCIe compatibility. You can add a second fan according to your preference, be it a another NF-A15 if you use standard height RAM or a 120 mm if you need more space. The idea was to give customers more flexibility in configuring the cooler to their needs, be it for maximum compatibility or maximum performance. So let’s look at this heatsink.