HP 631479-B21 Xeon E5640 2.66GHz Quad-Core Processor

Name: HP 631479-B21 Xeon E5640 2.66GHz Quad-Core Processor
Brand: HP
SKU: 631479-B21

A quad-core Xeon E5640 server processor upgrade kit with 12MB cache for HP ProLiant Gen6/Gen7 servers.

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Overview

The HP 631479-B21 is a processor upgrade kit featuring the Intel Xeon E5640, a quad-core server CPU built on Intel's Westmere architecture. Running at a base clock of 2.66GHz with a 12MB L3 cache and 5.86 GT/s QPI interconnect, the E5640 was designed for enterprise server environments that demand reliable multi-threaded processing. The processor supports hyper-threading, presenting eight logical threads to the operating system, which benefits virtualized environments, database servers, and multi-user applications where parallel workload handling is essential.

As an HP-branded kit (indicated by the B21 suffix), this product is engineered to drop directly into compatible HP ProLiant servers with the LGA 1366 socket, such as the DL360 G7 and DL380 G7 lines. The kit format typically includes the heatsink and mounting components matched to the specific server chassis, removing guesswork from the upgrade process. For organizations running legacy HP server infrastructure that still meets their needs, the E5640 provides a cost-effective performance boost — particularly in dual-socket configurations where two processors can work in tandem — without the expense of migrating to an entirely new server platform.

Specifications

Brand

Model

631479-B21

Processor

Intel Xeon DP Quad-Core E5640

Clock Speed

2.66GHz

Cores / Threads

4 Cores / 8 Threads

Cache

12MB L3

QPI Speed

5.86 GT/s

Socket

LGA 1366

Pros & Cons

👍 Pros

12MB L3 cache helps reduce memory latency for data-intensive server applications
Quad-core with hyper-threading provides eight threads for efficient multitasking
HP kit packaging ensures compatibility and includes necessary mounting hardware
Supports dual-socket configurations for scalable performance in multi-CPU servers

👎 Cons

Based on the older Westmere architecture with a 32nm process, consuming more power than modern server CPUs
2.66GHz base clock is slow by current standards, limiting single-threaded performance
Only compatible with LGA 1366 socket servers, which are end-of-life platforms
No support for DDR4 memory — limited to DDR3, which caps memory bandwidth

Frequently Asked Questions

What HP servers is the 631479-B21 processor compatible with?

This is an HP-branded processor kit designed for specific HP ProLiant server models. Check HP's compatibility matrix for your server model, as it is typically supported in ProLiant DL360 G7, DL380 G7, and similar Gen6/Gen7 platforms.

Is this a processor-only kit or does it include a heatsink?

HP processor kits with the B21 suffix typically include the processor and any necessary heatsink or mounting hardware required for the supported server chassis.

How many cores and threads does the Xeon E5640 provide?

The Xeon E5640 is a quad-core processor with hyper-threading, providing four physical cores and eight threads for improved multitasking in server workloads.

What is the QPI speed and why does it matter?

The E5640 has a QPI (QuickPath Interconnect) speed of 5.86 GT/s, which determines how quickly the processor communicates with other system components like memory and I/O. Faster QPI improves overall server responsiveness under heavy loads.

Can two of these processors be installed in a dual-socket server?

Yes, the Xeon E5640 supports multi-socket configurations. In a dual-socket HP ProLiant server, two E5640 processors can run together for a total of eight cores and sixteen threads.