A-Tech 4GB for HP HP Z400 Workstation (6 DIMM Slots) (1 x 4GB) PC3-12800 (DDR3-1600) ECC Unbuffered UDIMM 240-Pin 1Rx8 1.35V Server Memory RAM at Amazon.com
Managed to get an old HP Z400 workstation for the equivalent of $75 USD. Xeon W3520, 6x2gb of ram and I replaced the Quadro FX580 with a GT 730 I had laying
HP Z400 Xeon X5690 Processor Upgrade w/ 4 Memory Slot System Board - YouTube
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
Hp Z 400 mixed ram - HP Support Community - 7621103
4GB RAM Memory Upgrade for HP Workstation Z400 PC3-10600E DDR3 1333MHz 2Rx8 ECC Unbuffered UB DIMM Module (MemoryMasters) at Amazon.com