8GB (2 X 4GB) Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz Desktop DIMM RAM (PARTS-QUICK BRAND) Capacity: 8GB Kit (2 X 4GB) Form Factor: 240 pin DIMM Speed: PC3-10600 DDR3 1333MHz Halogen Free; ROHS; Warranty: Lifetime