CMS 8GB (2X4GB) DDR3 10600 1333MHZ ECC Non Registered DIMM Memory Ram Upgrade Compatible with HP/Compaq® Workstation Z400 Workstation for Server Only - B80 at Amazon.com
Solved: Z400 RAM - HP Support Community - 8063449
Solved: Z400 X5690 W3690 Fastest Processors - HP Support Community - 5683601
Solved: Z400 RAM Upgrade from 8GB to 12GB or 16GB - HP Support Community - 6746942
Upgrading an hp z400 (six slots) - HP Support Community - 7156445
HP Z400 12GB 3.2GHz Computers - Windows 10 | Like New, Low Price!
HP Z400 Computer FX625AV Intel Xeon CPU W3503@2.4GHz, 4GB, 160GBHDD WinVistaBusi | eBay