HP Z440 Workstation 4x4K Multi Monitors CPU 3.5GHz RAM 32GB SSD 512GB Win10 P600 [751489-006] - $819.00 : Professional Multi Monitor Workstations, Graphics Card Experts
8GB Memory for HP Workstation Z440, Z640, Z840 DDR4 PC4-17000 ECC RDIMM RAM | eBay
A-Tech 32GB Kit (2 x 16GB) for HP Z440 Workstation - DDR4 PC4-21300 2666Mhz ECC Registered RDIMM 1Rx4 - Server Memory Ram Equivalent to OEM 872970-001 872837-091 867855-B21 840757-091 815098-B21 at Amazon.com
RAM Update in Workstatino Z440 do not work - HP Support Community - 6881802
parts-quick 16GB Memory for HP Z440 Workstation DDR4 PC4-17000 2133 MHz RDIMM RAM at Amazon.com