4GB 2X2GB RAM Memory for Dell OptiPlex 780 (Performance Mini Tower ) DDR3 DIMM 240pin PC3-8500 1066MHz Black Diamond Memory Module Upgrade - Walmart.com
Dell OptiPlex 780 USFF with 19" Monitor ,WiFi 650MB/s, 320GB HDD, 4GB RAM, USB Mouse & Keyboard, Windows 10 Pro. Used with 1 year Warranty. - Walmart.com
Dell OptiPlex 780 MT Intel Core 2 Quad Q9400 2.66GHz 2GB RAM NO HDD NO OS | eBay
UPDATE MEMORY RAM DELL OPTIPLEX 780 - YouTube
Tried upgrading optiplex 780 ram, wont turn on - Dell Community
Restored Dell Optiplex 780 Windows 10 Home Premium Desktop PC Tower Core 2 Duo 3.0GHz Processor 8GB RAM 500GB Hard Drive DVD-RW Wifi with a 19" LCD- Computer (Refurbished) - Walmart.com
2GB Memory Upgrade for Dell Optiplex 780 DT/MT/SFF DDR3 PC3-10600 1333MHz DIMM Non-ECC Desktop RAM (PARTS-QUICK Brand) at Amazon.com
4GB KIT 2 x 2GB Memory for DELL OptiPlex 3010 380 390 580 780 790 7900 9010 RAM | eBay