840757-091 is the HPE assembly part number for 16GB (1x16GB) Single Rank x4 DDR4-2666 CAS-19-19-19 Registered Smart Memory Kit. This is the number printed on the module label and returned by HPE PartSurfer lookups, so it is what you will see when identifying a module already installed in a server. The module is a 288-pin DDR4 registered DIMM rated at 2666 MHz, PC4-21300, CL19 with 19-19-19 timings, single rank x4 organization, 2048 x 72 configuration, ECC, and 1.2 V operation. It carries HPE SmartMemory branding.
HPE Option Part #: 815098-B21
HPE Spare Part #: 850880-001
HPE Assembly Part #: 840757-091
PRODUCT SPECIFICATIONS FOR 840757-091:
- Brand: HPE
- Product Line: HPE, HPE SmartMemory
- Type: DRAM
- Product Type: Memory module
- Form Factor: DIMM 288-pin
- Technology: DDR4 SDRAM
- Storage Capacity: 16 GB
- Registered or Buffered: Registered
- Data Integrity Check: ECC
- Module Configuration: 2048 x 72
- Chips Organization: X4
- Memory Speed: 2666 megahertz
- Memory Specification Compliance: PC4-21300
- Supply Voltage: 1.2 volt
- CAS Latency: CL19
- Latency Timings: 19-19-19
- RAM Features: Single Rank
RESOURCES FOR 840757-091 (815098-B21)
Quickspecs for 815098-B21COMPATIBLE WITH:
PROLIANT BL SERIES
PROLIANT DL SERIES
PROLIANT ML SERIES
PROLIANT XL SERIES
** This list may not be complete. Contact us via Live Chat if you have any questions about compatibility.
FREQUENTLY ASKED QUESTIONS ABOUT 840757-091
What is the difference between 840757-091, 815098-B21 and 850880-001?
All three identify the same physical 16GB single rank x4 DDR4-2666 registered DIMM. 840757-091, the number on this page, is the assembly part number, typically printed on the module label and shown in HPE PartSurfer. 815098-B21 is the option part number used when ordering the kit through HPE channels. 850880-001 is the spare part number used for service replacement. The module itself does not change between them.
How do I confirm a module in hand matches this page?
Check the label for 840757-091 and the printed specifications. The module should read as a 16 GB DDR4 registered DIMM, 288-pin, rated 2666 MHz and compliant with PC4-21300, at 1.2 V. Additional identifying details are single rank, x4 chip organization, ECC support, a 2048 x 72 module configuration, and CAS latency CL19 with 19-19-19 latency timings.
Which servers use this module?
This DIMM is listed for HPE Gen10 platforms with first generation processors: BL460c Gen10, DL360 Gen10, DL380 Gen10, DL560 Gen10, DL580 Gen10, ML110 Gen10, ML350 Gen10, XL170r Gen10 and XL190r Gen10. If the server you are verifying against uses a later processor generation, confirm against that platform's own memory documentation before reusing the module.
What does Registered and ECC mean on this label?
Registered means the module includes a register that buffers address and command signals between the memory controller and the DRAM chips, which is standard for server memory. ECC indicates error checking and correction support, reflected in the 2048 x 72 module configuration where the additional bits beyond a 64-bit data path carry ECC information. Both are required characteristics on the platforms this module is listed for.
Is single rank x4 significant when matching modules?
Yes. This module is single rank with x4 DRAM organization, and those attributes affect how a server populates and clocks its memory channels. When verifying against modules already installed, compare rank and organization as well as capacity and speed, since a 16 GB DDR4-2666 DIMM with different rank or chip organization is not the same part as 840757-091.
HPE PARTSURFER INFO FOR 840757-091 (815098-B21)
| Spare PN | Description | |
|---|---|---|
 | 850880-001 | 16GB PC4-2666V-R, registered synchronous dynamic random access memory (SDRAM) 2Gx4, operated in a dual data rate (DDR4) mode, packaged in a dual in-line memory module organized as 2Gx72 ; |
Last Updated: 2026-07-28
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This product is warrantied against hardware failure for a period of 5 Years from the date of purchase. Before making a purchase, please take a moment to review our return policy below.
Returns
It is the customer's responsibility to verify compatibility with their machine(s) before placing an order. If an item is ordered by mistake, it can be returned for refund, minus a 25% restocking fee, within 5 business days of receipt. The cost of freight is not refundable.
Please be aware that factory-sealed equipment can only be returned if it remains unopened.
Defective Products
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In case your hardware becomes defective during the Global One warranty period, but the HPE warranty has expired, you can return the product to us for a working replacement. You are responsible for the shipment of returned merchandise. However, we will cover the expense of Ground /Economy shipment for the replacement item(s).
Requesting an RMA
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