INSIDE YOUR HP Z820 WORKSTATION TOWER. Your machine can take three different types of Ram, ECC UDimm, ECC RDimm and ECC LRDimms. You can not mix and match different types. Max Upgrades are as follows UDimm = 128GB (16x8GB), RDimm = 512GB (16x32GB) and LRDimms = 512GB (16x32GB).
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