Product Detail 4GB 1066MHz memory kit (2x2GB) 8-layer PCB for better reliability Lifetime warranty . The "G.Skill PK Series - Memory - 4 GB : 2 x 2 GB - DIMM 240-pin - DDR2 - 1066 MHz / PC2-8500 - CL5 - 2.0 - 2.1 V - unbuffered - non-ECC" is best product for you. We recommended G.Skill PK Series - Memory - 4 GB : 2 x 2 GB - DIMM 240-pin - DDR2 - 1066 MHz / PC2-8500 - CL5 - 2.0 - 2.1 V - unbuffered - non-ECC