16GB KIT (4 x 4GB) for HP-Compaq Z Workstation Series Z200 Z400 (4 DIMM Slots) Z400 (6 DIMM Slots). DIMM DDR3 ECC Registered PC3-10600E 1333MHz Dual Rank Server Ram Memory. Genuine A-Tech
CMS 8GB (2X4GB) DDR3 10600 1333MHZ ECC Non Registered DIMM Memory Ram Upgrade Compatible with HP/Compaq® Workstation Z400 Workstation for Server Only - B80
4GB EUDIMM Memory for HP Z400 Workstation DDR3L-1600 - Newegg.com
Solved: Z400 RAM - Page 2 - HP Support Community - 6148900
24GB (6 x4GB) Memory DDR3 1333 PC3 10600 ECC for HP Workstation Z400 w 6 sockets - Newegg.com