4GB Memory for HP ProDesk 400 G3 Microtower PC DDR4 2133MHz DIMM RAM (PARTS-QUICK Brand) at Amazon.com
Amazon.com: HP Prodesk 400 G3 Mini Tower Computer, Intel Core I3-6100 3.7GHz, 12G DDR4, 1T SSD, DVD, WiFi, BT, DP, VGA, Windows 10 Pro 64 Bit-Multi-Language Supports English/Spanish/French (Renewed) : Electronics
Amazon.com: HP ProDesk 400 G3 Small Form Factor, Intel Core Quad i5 6500 up to 3.6 GHz, 16GB DDR4, 512GB SSD, WiFi, BT 4.0, DVDRW, VGA, DP, Windows 10 Pro 64-Multi-Language Support
Amazon.com: HP ProDesk 400 G3-SFF, Core i5-6500 3.2GHz, 8GB RAM, 256GB Solid State Drive, Windows 10 Pro 64bit, (RENEWED) : Electronics