Part Number: 00D4970-AM (Addon 16gb ddr3-1600mhz dr rdimm) Part Number: 00D4980-AM (Addon 8gb ddr3-1333mhz sr rdimm ) Part Number: 00D4981 (No description) Part Number: 00D4981-AM (Addon 8gb ddr3-1333mhz sr rdimm ) Part Number: 00D4981-AX (Axiom 8gb ddr3-1333 ecc low volt) Part Number: 00D4981-AXA (Axiom ibm supported 8gb module -) Part Number: 00D4985 (No description) Part Number: 00D4985-AM (Addon ibm 00d4985 compatible fac) Part Number: 00D4987 (No description) Part Number: 00D4988-AM (Addon 8gb ddr3-1600mhz sr rdimm ) Part Number: 00D4989-AX (Axiom 8gb ddr3-1600 ecc vlp rdim) Part Number: 00D4989-AXA (Axiom ibm supported 8gb module -) Part Number: 00D4993 (No description) Part Number: 00D4993-AM (Addon ibm 00d4993 compatible fac)