Mushkin 976552A DDR2 FBDIMM (2x2GB) 4GB PC2-5300 FB Xserve Apple OE 5-5-5-15 MAC PRO FB 1.8V Compatible Frequency This product is engineered to operate at the optimum frequency for compatibility with your system. Compatible Timings This product is programmed to use timings that offer maximum compatibility with your system and original memory. Dual Channel Kit Engineered for dual-channel architecture. Lifetime Warranty Quality guaranteed - we offer a lifetime warranty on this product and genuine, unmatched service and support. Type: DDR2 FBDIMM Voltage: 1.8V Speed Spec: PC2-5300 Frequency: 667MHz Capacity Kit Type: Dual Kit Module Size: 2GB Timings tCL: 5 tRCD: 5 tRP: 5 tRAS: 15 Cooling Technology Heatsink: Buffered