HP 647899-B21 8GB (1x8GB) PC3-12800R DDR3-1600 Memory Kit

Name: HP 647899-B21 8GB (1x8GB) PC3-12800R DDR3-1600 Memory Kit
Brand: HP
SKU: 647899-B21

Overview

The HP 647899-B21 is an 8GB registered DDR3-1600 memory module designed for use in HP ProLiant servers and compatible enterprise systems. As an HP-qualified part, it has been tested and validated to work within HP's server ecosystem, providing peace of mind for administrators who need guaranteed compatibility and support. The module operates at PC3-12800R speeds with CAS-11 latency and includes ECC (Error Correcting Code) functionality, which detects and corrects single-bit memory errors to maintain data integrity in production environments.

This single-rank DIMM is well suited for expanding memory in Gen8-era ProLiant servers that are still in active service. Its registered design allows the server's memory controller to handle larger numbers of DIMMs per channel, which is essential when scaling up total system memory. While DDR3 is no longer the current standard, many organizations continue to operate servers built on this platform, and sourcing HP-branded modules ensures firmware-level compatibility without triggering memory mismatch warnings. For environments running virtualization, databases, or application servers on older ProLiant hardware, this module provides a cost-effective upgrade path.

Key Features

Genuine HP Branded 664691-001 8GB Memory. (1x8GB). 1Rx4 PC3-12800R

Specifications

Capacity

8GB (1x8GB)

Memory Type

DDR3

Speed

1600MHz (PC3-12800R)

Rank

Single Rank

Error Correction

Registered (ECC)

CAS Latency

CAS-11

HP Part Number

647899-B21

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Pros & Cons

👍 Pros

HP-qualified part number ensures tested compatibility with HP ProLiant server platforms.
DDR3-1600 speed provides solid bandwidth for server workloads at this generation level.
Registered ECC design supports error correction and stable operation in mission-critical environments.
Single-rank configuration can allow for higher total DIMM population per memory channel.

👎 Cons

8GB capacity is relatively small by current server standards, potentially requiring multiple modules for adequate total memory.
DDR3 is a previous-generation memory technology, not compatible with newer DDR4 or DDR5 server platforms.
Registered DIMMs are not compatible with standard desktop motherboards or unbuffered memory slots.
Single module provides no redundancy—a multi-DIMM configuration is needed for interleaved performance.

Frequently Asked Questions

What servers is the HP 647899-B21 memory module compatible with?

This is an HP-qualified module designed for HP ProLiant Gen8 servers and similar systems that accept PC3-12800R DDR3 registered DIMMs. Check your server's documentation to confirm compatibility before purchasing.

What does "Registered" mean for this memory module?

Registered (also called buffered) memory includes a register between the memory chips and the memory controller, which improves signal integrity and allows servers to support larger total memory capacities. It is standard in server and workstation environments.

Can I mix this 8GB module with other memory sizes in my server?

While it is technically possible, mixing DIMM sizes can affect memory interleaving and performance. For optimal performance, it is recommended to populate memory channels with identical modules.

What is the CAS latency of this module and why does it matter?

This module has a CAS latency of 11 (CL11). CAS latency indicates the delay between a memory access request and data availability—lower numbers mean slightly faster access, but for server workloads the difference between CL values is generally minimal.