HPE 64GB Dual Rank 2Rx4 PC5-6400B-R Registered Smart Memory
Fits 6 HPE ProLiant server models. See the list
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Part number cross-reference
- Part number
- P64986-B21
Overview
P64986-B21 is the HPE option part number for 64GB Dual Rank 2Rx4 PC5-6400B-R Registered Smart Memory. It is a 288-pin DDR5 RDIMM running at 6400 MHz (PC5-6400B-R) with CL46 timings (46-39-39), built as a dual rank, registered module with x4 chip organization. HPE lists it for the DL325 Gen11, DL345 Gen11, DL365 Gen11 and DL385 Gen11 when configured with 5th Gen processors. If you are quoting to a configuration or expanding an existing population, the option number is the one that normally appears on an HPE configuration or quote, so it is the reference to match when specifying additional 64GB DDR5 capacity.
HPE Option Part #: P64986-B21
HPE Spare Part #: P65248-001
HPE Assembly Part #: P69721-1A1
PRODUCT SPECIFICATIONS FOR P64986-B21:
- Capacity: 64 GB
- Width: 3.5 in
- Depth: 7.5 in
- Height: 0.8 in
- Weight: 1.41 oz
- Type: DRAM memory module
- Technology: DDR5 SDRAM
- Form Factor: RDIMM 288-pin
- Speed: 6400 MHz (PC5-6400B-R)
- Latency Timings: CL46 (46-39-39)
- Features: Dual Rank, registered
- Chips Organization: X4
COMPATIBLE WITH:
PROLIANT DL SERIES
** This list may not be complete. Contact us via Live Chat if you have any questions about compatibility.
FREQUENTLY ASKED QUESTIONS ABOUT P64986-B21
Which servers does P64986-B21 fit?
This module is listed for the HPE ProLiant DL325 Gen11, DL345 Gen11, DL365 Gen11 and DL385 Gen11, in each case with 5th Gen processors installed. The processor generation matters because DDR5 memory support is tied to the CPU's integrated memory controller. If your server is one of these four models with a 5th Gen CPU, P64986-B21 is the matching 64GB registered DDR5 option.
What are the exact specifications of this module?
P64986-B21 is a 64GB DRAM module using DDR5 SDRAM technology in a 288-pin RDIMM form factor. It runs at 6400 MHz and carries the PC5-6400B-R designation, with latency timings of CL46 (46-39-39). The module is dual rank (2Rx4) and registered, with x4 chip organization. Physical dimensions are 7.5 in deep by 3.5 in wide by 0.8 in high, weighing 1.41 oz.
What is the difference between P64986-B21 and P65248-001?
They are the same physical memory module under two different HPE numbering schemes. This page, P64986-B21, is the option part number: the orderable number used on configurations and quotes. P65248-001 is the spare part number, the reference HPE uses for service replacement of an already-installed module. This family also includes one assembly revision, shown in the cross-reference block on the page. An assembly part number identifies a manufacturing-level build of the same module.
What does dual rank 2Rx4 mean for my configuration?
2Rx4 describes the module's internal organization: two ranks of DRAM with x4 chip width. Rank count and chip organization affect how a server populates its memory channels and how modules can be mixed within a configuration. Because P64986-B21 is a registered (RDIMM) module, address and command signals are buffered through a register, which is standard for the ProLiant Gen11 platforms this module is listed for.
Can I mix P64986-B21 with other memory already in the server?
Use the memory population rules published for your specific server model. P64986-B21 is a 64GB dual rank, registered DDR5 RDIMM rated at 6400 MHz with CL46 timings, and mixing modules of differing capacity, rank or speed within a system is governed by those rules. The safest approach when expanding is to match the installed modules' capacity, rank and speed to the specifications listed here.
Last Updated: 2026-10-22
Other sizes in this family
| Part number | Capacity | Type | Rank | Price | Availability |
|---|
Working out how many you need? Each server's memory page counts the modules for the capacity you want: see Compatible servers.
Specifications
Compatible servers
Each server opens that model's memory page, with its slot rules and a kit picker.
Part numbers
Every number below identifies this same part. Match any of them to the label on the part you are replacing.
Questions about P64986-B21
Warranty and returns
5-year replacement warranty
Covered against hardware failure for 5 years from the date of purchase. While HPE's own warranty runs, HPE replaces a failed part through the HPE Enterprise Support Center. After that, send it back to us for a working replacement; you ship it to us and we pay Ground or Economy shipping on the replacement.
Ordered the wrong part?
It is the customer's responsibility to verify compatibility before ordering. A part ordered by mistake can be returned for a refund, less a 25% restocking fee, within 5 business days of receipt. Freight is not refunded, and factory-sealed items can only be returned unopened. Check Compatible servers before you order.
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P64986-B21 HPE 64GB Dual Rank 2Rx4 PC5-6400B-R Registered Smart Memory
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