Tailored to provide superior RAM & PCIe compatibility, the NH-D15S is an asymmetrical single fan version of Noctuas award-winning flagship model, the NH-D15. Thanks to its asymmetrical design, the NH-D15S clears the top PCIe slot on most Micro-ATX & ATX motherboards. At the same time, the single fan setup & recessed lower fins guarantee 100% RAM compatibility with memory modules of up to 65mm height. Users who have sufficient room can also upgrade the cooler with either a 120mm or round 140mm fan on the front fin stack for further enhanced performance in dual fan mode. Topped off with the trusted, pro-grade Secu Firm 2 multi-socket mounting system, Noctuas proven NT-H1 thermal compound & full six year manufacturers warranty, the NH-D15S forms a complete premium quality solution that combines dual tower efficiency with excellent compatibility & flexible upgrade options. High-compatibility version of NH-D15 Compared to the award-winning NH-D15, the S-version uses an off-set, asymmetrical layout & a single instead of dual NF-A15 fans. This allows the NH-D15S to provide state-of-the-art heatsink performance while maintaining superior RAM & PCIe compatibility. Excellent RAM compatibility Thanks to its recessed lower fins, the NH-D15S provides 65mm clearance for tall memory heatsinks, making it compatible with most high end modules on the market. As the lower fins are recessed on both sides of the heatsink, compatibility is excellent not only on LGA115x & AMD, but also on LGA2011 where there are RAM slots on both sides of the socket. Asymmetrical layout for better PCIe compatibility As many current motherboards have the top PCIe x 16 slot sitting close to the socket, bigger heatsinks tend to block it. Due to its asymmetrical layout, the fin-stack of the NH-D15S is off-set towards the upper edge of the motherboard when installed in standard orientation. This allows it to clear the top PCIe x 16 slot on most current µATX & ATX motherboard. Please refer to our motherboard compatibility list for detailed information. NF-A15 140mm fan Complying with Noctuas AAO standard & featuring sophisticated aerodynamic design measures such as Flow Acceleration Channels, the NF-A15 has quickly built up a reputation as one of the best 140mm fans on the market. Dual-fan ready Using the supplied extra fan clips, the NH-D15S can be upgraded with either a second round-frame 140mm fan with 120mm mounting holes (such as the NF-A15) for maximum performance or a common 120mm fan (such as the NF-F12) for improving performance while maintaining compatibility with RAM modules of up to 45mm height. PWM support & Low-Noise Adaptor The NF-A15 premium fan supplied with the NH-D15S supports PWM for convenient automatic speed control through the motherboard. In addition, the maximum fan speed can be reduced from 1500 to 1200rpm using the supplied Low-Noise Adaptor for even quieter operation. Excellent component cooling Extending below the fin-stacks, the large NF-A15 fan not only contributes to the superb CPU cooling capabilities of the NH-D15S but also provides massive airflow over surrounding motherboard components & heatsinks, thus ensuring excellent component cooling performance. Secu Firm 2™ mounting system Noctuas Secu Firm 2 mounting systems have become synonymous with quality, safety & ease of use. Supporting Intel LGA115x (LGA1150, LGA1151, LGA1155, LGA1156), LGA2011 (LGA2011-0 & LGA2011-3), LGA2066 & AMD (AM3 (+), AM2 (+), FM1, FM2 (+)), the Secu Firm 2 mounting included with the NH-D15S guarantees perfect contact pressure & maximum convenience on all current sockets.