12GB KIT (6 x 2GB) for HP-Compaq Z Workstation Series Z400 (6 DIMM Slots). DIMM DDR3 ECC Unbuffered PC3-10600E 1333MHz Server Ram Memory. Genuine A-Tech Brand. at Amazon.com
Hp Z 400 mixed ram - HP Support Community - 7621103
HP Z400 RAM Upgrade– Cloud Ninjas
HP Z400 Workstation Xeon 3.3 GHz - HDD 500 GB RAM 8GB | Back Market