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
OFFTEK 1GB Replacement Memory RAM Upgrade for Dell OptiPlex 390 (Desktop) (DDR3-10600 - Non-ECC) Desktop Memory at Amazon.com
Dell Optiplex 390 – RefurbIT
OptiPlex 390 Removal Guide for the Memory, Fan Shelter, System Fan, Power Switch Cable and Coin Cell battery | Dell US
8GB (2 X 4GB) Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz Desktop DIMM RAM (PARTS-QUICK Brand) at Amazon.com
CMS 8GB (2X4GB) DDR3 10600 1333MHZ Non ECC DIMM Memory Ram Upgrade Compatible with Dell® Optiplex 390 Ddr3 Dimm - A69 at Amazon.com