Restored Dell OptiPlex 780 SFF Desktop PC with Intel Core 2 Duo Processor, 4GB Memory, 250GB Hard Drive and Windows 10 Pro (Monitor Not Included) (Refurbished) - Walmart.com
4GB DDR3 Memory Upgrade for Dell Optiplex 780 DT/MT/SFF PC3-8500 240 pin 1066MHz Desktop RAM (PARTS-QUICK Brand) at Amazon.com
Dell Optiplex 780 Small Form Factor - iFixit
Dell Optiplex 780 SFF Core 2 Duo 3.0 GHz - HDD 1 TB RAM 8GB | Back Market
OptiPlex 780 Ultra Small Form Factor(USFF) Removal Guide for the Memory, System Fan, Heatsink, Intrusion Switch and Power Supply | Dell US