CMS 8GB (2X4GB) DDR3 10600 1333MHZ Non ECC DIMM Memory Ram Upgrade Compatible with Dell®
Best Buy: CMS 8GB (2x4GB) Memory RAM Compatible with Dell Optiplex 990 DT / MT / SFF, Ultra CM5126410600DIMMX20201
Dell Optiplex 990 Desktop Computer PC, 3.20 GHz Intel i5 Quad Core Gen 2, 4GB DDR3 RAM, 250GB SATA Hard Drive, Windows 10 Professional 64bit (Renewed) | Popular Science
Dell Optiplex 990 Tower Computer PC, 3.20 GHz Intel i5 Quad Core Gen 2, 16GB DDR3 RAM, 2TB SATA Hard Drive, Windows 10 Professional 64bit (Renewed) | Citizen Goods