Hi,
HP MSR4000 MPU-100 Main Processing Unit (JG412A) comes with default=2GB of SDRAM.
It can be upgraded to a maximum 4GB DDR SDRAM (4GB Max, by replacing existing single 2GB SDRAM)
The following DDR SDRAM install into this Module:
HP X610 4GB DDR3 SDRAM UDIMM Memory (Must remove existing 2GB UDIMM to install the 4GB UDIMM)
Refer the quick specs: https://h20195.www2.hpe.com/v2/getpdf.aspx/c04315129.pdf?ver=12
Thank you