Adamanta 64GB (4x16GB) Server Memory Upgrade for HP Z840 Workstation DDR4 2133MHz PC4-17000 ECC Registered Chip 2Rx4 CL15 1.2V RAM 64GB ( 4x16GB ) DDR4 2133 MHz ECC Registered/Buffered 288pin Standard Voltage Dual Rank Random Access Memory Module. Every module is backed by a limited lifetime warranty from the manufacturer. We always have hundreds in stock! Free technical support from our experienced technicians. Not compatible with desktop PCs. Will only work with servers and select workstations Every single module is fully tested by the manufacturer and certified. Compatible with most major brand servers. Not sure if your server is compatible? Feel free to contact us. Our experienced technicians can verify if these parts will work for you.