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
32GB (4X8GB) DDR3 1333 Memory For HP Z400 Z420 Workstation | eBay
HP Z400 Workstation MT Intel Xeon W3550 3.07GHz 8GB RAM No HDD No OS