Solved: Z400 RAM - Page 2 - HP Support Community - 6148900
HP Workstation Z400 Memory Upgrades @Memory.NET
A-Tech 24GB ECC Unbuffered Memory Kit (6 x 4GB) for HP Z400 Workstation - ECC UDIMM DDR3 PC3-10600 1333MHz 240-Pin DIMM 2Rx8 1.5V Dual Rank RAM (AM080899) at Amazon.com
INFO PC - HP WorkStation z400 Intel Xeon W3520 Cpu 2.66 GHz Max Turbo Frequency 2.93 Ghz Ram Memory 8GB Hard Drive 500 GB Grafik Quadro Fx600 1 GB Dedicated Qmimi: 219 Euro | Facebook
4GB RAM Memory Upgrade for HP Workstation Z400 PC3-10600E DDR3 1333MHz 2Rx8 ECC Unbuffered UB DIMM Module (PARTS-QUICK Brand) at Amazon.com