A Closer Look at the Noctua NH-D15S
Aside from the prominent lean, the NH-D15S is almost physically identical to the NH-D15. There are also six 6mm heatpipes that distribute heat to 45 aluminum fins with the bottom seven aluminum fins clipped so as to provide the 64mm RAM module height clearance. Like the NH-D15, the sides are folded and closed off so that airflow is focused through the body unlike the NH-D14’s aluminum fin array which are open on all sides.
Since the base is offset, the heatpipe closest to the base is protruding at the top while the heatpipe at the other end is burrowed. The fin design has also changed to help with thermal efficiency as well as lowering turbulence. The fins slope into a center point to minimize airflow deadzone caused by the center fan hub and the sides are folded so airflow is concentrated on the center area.
The contact surface is flat, reflective and has visible round micro-machine marks which makes it suitable for more viscous thermal compounds such as Noctua’s NT-H1. The surface area measures 40 x 38mm, suitable for coverage of even the large LGA2011 CPU integrated heatsink surface area. The nickel plate finish prevents oxidation of exposed copper and also contributes to the premium feel of the build quality.
The bundled Noctua NF-A15 fan has a 140mm frame but has dual mounting holes for standard 140mm and 120mm with 105mm spacing. It already comes pre-installed and thus already comes with a pair of wire fan mounting clips. The retail NF-A15 can be purchased for around $25-$30 USD two of these fans alone are worth half of the NH-D15 retail price if bought separately, hence bundling only one allows Noctua to offer it at a much lower price.
The NF-A15 fans feature the latest in Noctua fan technology including SSO2 bearing, inner surface microstructures, stepped-inlet design, and flow-acceleration channels. SSO2 stands for 2nd generation Self-Stabilizing Oil-pressure bearing technology which is essentially an oil-based hydrodynamic bearing with a self-stabilizing magnet in the rear of the brass bearing shell. The stepped-inlet design of the frame allows more air to be drawn in while the flow-acceleration channels on the seven-bladed NF-A15 works in conjunction with the inner-surface micro-structures to improve airflow while minimizing noise caused by turbulence. Unlike the retail NF-A15 fan which runs at 1200 RPM, the one bundled on the Noctua NH-D15S is similar to the one bundled with the NH-U14S and NH-D15 and runs at a higher 1500R PM max.
The fan cable is nicely sleeved and has a black 4-pin connector, Readings from ASUS Fan Xpert II reveal the real-world controllable PWM range: