SESX2C1Z 8GB Memory Expansion (2 × 4GB) X-Option, RoHS:Y 501-7954 4GB DDR2-667/PC2-5300 DIMM, RoHS:Y SESX2B2Z 4GB Memory Expansion (2 × 2GB) X-Option, RoHS:Y 511-1161 2GB DDR2-667/PC2-5300 FBDIMM, RoHS:Y