Mushkin Enhanced 4GB (2 x 2GB) DDR2 667 (PC2 5300) ECC Fully Buffered Dual Channel Kit Memory for Apple Server & Mac Pro Model 976539A Type: 240-Pin DDR2 FB-DIMM Compatibility: For Apple Server & Mac Pro Cas Latency: 5 Timing: 5-5-5-15 Voltage: 1.8V Multi-channel Kit: Dual Channel kit Heat Spreader: Yes Parts: Lifetime limited