Based on Noctua's signature NH-U12 series and fitted with the award-winning NF-P12 fan and NT-H1 thermal compound, the NH-U12DX 1366 forms a complete premium quality package that provides outstanding quiet cooling performance for Intel's LGA1366 Xeon 5500 CPUs. The new SecuFirm2 mounting system for LGA1366 is highly convenient and makes the NH-U12DX 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-U12DX 1366 works as a simple drop-in replacement. Featuring psychoacoustic optimizations and Noctua's premium-grade SSO-bearing, the award-winning NF-P12 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-U12DX 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. Please choose the NH-U12P SE2 for these mainboards.