 4GB 667MHz DDR2 ECC fully-buffered DIMM (FB-DIMM) memory
These modules are 100% compatible with the Xserve machines with Dual-Core Intel Xeon 5100 processors and they meet Apple's robust thermal specifications for Xserve FB-DIMMs.
Small Heat Sinks are required in xServe intel machines as bigger heat sink FB-DIMMs will not fit. | 
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