SK hynix · Server memory
HMA84GR7CJR4N-VK
32 GB DDR4-2666 ECC Registered DIMM (RDIMM), dual-rank ×4. Sold by HP and HPE under their own part numbers, all cross-referenced below.
Specifications JEDEC / manufacturer data
| Memory type | DDR4 | catalog |
| Module type | RDIMM · ECC Registered DIMM | catalog |
| Capacity | 32 GB | catalog |
| Speed | DDR4-2666 · PC4-21328 | catalog |
| Organization / rank | 2Rx4 | catalog |
| Voltage | 1.2 V | JEDEC standard for DDR4 |
| Form factor | 288-pin DIMM | standard for DDR4 RDIMM |
OEM part numbers same module, OEM-branded
| Vendor | OEM part number | Verification |
|---|
| HP | 840758-091 | catalog |
| HPE | 815100-B21 | ✓ verified |
| HPE | 850881-001 | ✓ verified |
OEM cross-references are compiled from distributor cross-reference data and OEM documentation. Verify against your vendor's parts list before ordering.
Compatible alternatives same JEDEC specification
Modules match on all key specifications (type, form factor, capacity, speed, rank organization) and are generally interchangeable in servers that accept this spec.
Interchangeability is based on matching JEDEC specifications, not per-server testing. Confirm against your server vendor's qualified parts list.
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Frequently asked
Is HP 840758-091 the same module as HMA84GR7CJR4N-VK?
Yes. HP resells this SK hynix module under part number 840758-091; HPE does the same as 815100-B21, HPE does the same as 850881-001. The physical module is identical: OEM part numbers are branding, not different hardware.
Can I use a Kingston or Micron module instead?
In most servers, yes: 9965640-033.C00G (Kingston), MTA36ASF4G72PZ-2G6 (Micron), MTA36ASF4G72PZ-2G6D1 (Micron) match this module on every key specification (32 GB, DDR4-2666, RDIMM, 2Rx4). Keep vendors consistent within a memory bank, and check your server's qualified parts list for edge cases.
What does 2Rx4 mean?
Two ranks of DRAM chips, each 4 bits wide ("×4"). Rank organization affects how many modules a memory controller can drive at full speed, so it's listed as a key spec.