2GB Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz DIMM Non-ECC Desktop RAM (PARTS-QUICK Brand) at Amazon.com
Dell Optiplex 390 Desktop | Intel i5 Processor | 4GB RAM | 250GB HDD | WIFI | Windows 10 Pro
Restored Dell OptiPlex 390-T Desktop PC with Intel Core i5-2400 Processor, 8GB Memory, 500GB Hard Drive and Windows 10 Home (Monitor Not Included) (Refurbished) - Walmart.com
8GB (2 X 4GB) Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz Desktop DIMM RAM (PARTS-QUICK Brand) at Amazon.com