Based on Noctua's compact NH-U9 series and fitted with the award-winning NF-B9 fan and NT-H1 thermal compound, the NH-U9DX 1366 forms a complete premium quality package that provides excellent quiet cooling performance for 4U Xeon 5500 (LGA1366) workstations and servers. The new SecuFirm2 mounting system for socket LGA1366 is highly convenient and makes the NH-U9DX 1366 a tailor-made drop-in replacement for standard Intel coolers. To make your Xeon 5500 systems quieter has never been so easy! Completely pre-installed, the new SecuFirm2 mounting system ensures maximum convenience and extremely short installation time. SecuFirm2 for Socket LGA1366 is fully compatible with the original Intel installation system so the NH-U9DX 1366 works as a simple drop-in replacement. Featuring psychoacoustic optimizations and Noctua's premium-grade SSO-bearing, the award-winning NF-B9 is renowned for its exceptional quietness and long-term stability. Noctua's much-acclaimed NT-H1 is a pro-grade TIM solution that provides minimum thermal resistance, excellent ease-of-use and outstanding reliability. Caution: The NH-U9DX 1366 can only be used on mainboards that have a backplate with screw threads for CPU cooler installation (such as the Intel reference backplate for Xeon 5500). The cooler is thus incompatible with Xeon 3500 and Core i7 mainboards that don?t have such a backplate.