2GB Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz DIMM Non-ECC Desktop RAM (PARTS-QUICK Brand) at Amazon.com
8GB (2 X 4GB) Memory Upgrade for Dell Optiplex 390 DDR3 PC3-10600 1333MHz Desktop DIMM RAM (PARTS-QUICK Brand) at Amazon.com
Amazon.com: Dell Optiplex 390 Business High Performance SFF Desktop Computer PC (Intel Quad-Core i5-2400 up to 3.4GHz, 8GB DDR3, 1TB HDD, HDMI, DVD, Windows 10 Pro 64-bit) (Renewed) : Electronics
Dell Optiplex 390 Desktop | Intel i5 Processor | 4GB RAM | 250GB HDD | WIFI | Windows 10 Pro
Upgrade PC Dell OptiPlex 390 SSD and Ram 8GB - YouTube