HP N4000 (rp7400)

Quick Facts
Introduced 1999-2001
CPU 1-8 PA-8500/
1-8 PA-8600/
1-8 PA-8700
360-750 MHz
Caches 1.5-2.25 MB L1
Design Stretch
Drives 2 SCSI
Expansion 12 PCI
Bandwidth System 4.2 GB/s
CPU 17 GB/s
Mem 8.5 GB/s
I/O 6.4 GB/s
XBAR 15.3 GB/s
3 serial
100E console


The rp7400 were the original version of the N4000 line of servers — the newer rp7405 and rp7410 servers were also labeled as N4000 and feature a similar set of I/O options and expandability in basically the same chassis. However the original N4000, the rp7400 described here, is based around a different system architecture than their sucessors — the Stretch chipset, also used in the L1500 and L3000 (rp5430/rp5470) servers.

The original N4000s were shipped in two models, with differences in their system board — A3639A and A3639B. The N4000 which was later renamed to rp7400 was shipped with an even different mainboard and had the model number A3639C.

Model numbers: all the N4000-36, N4000-44, N4000-5X, N4000-6X and N4000-7X have the rp7400 model number.



The rp7400 N4000 supports one to eight processors.

The original N4000 (A3639A and A3639B) and later rp7400 (A3639C) are in fact different products, based on the same basic architecture but with slight differences, especially relating to the type and number of processors. Not all early N4000s support the later processors and a maximum number of CPUs.

Processor types are indicated with the following suffixes:


The rp7400 system is based on the Stretch chipset, used in the L1500 and L3000 (rp5430/rp5470) servers as well. Stretch has four main components:

  1. Prelude memory controller attaches the memory via two memory buses to the two main system buses; Prelude is the main crossbar of the system
  2. Four DEW Runway converters attach the up to eight Runway-based CPUs to the main system buses; two CPUs share one DEW port converter
  3. Two IKE I/O controllers connect the PCI bridges via I/O channels to the system buses
  4. 14 Elroy PCI bridges (LBAs) which convert the I/O channels from the IKE I/O controllers into PCI buses for the I/O subsystem and expansion slots

The rest of the system is implemented with common parts used in other HP 9000 servers as well:

» View a system-level illustration (ASCII) of the N4000’s system/bus architecture.


The system bus architecture is interesting as it provided more theoretical bandwidth than could be used under practical circumstances. The designers probably counted on future CPU upgrades, such as Itanium processors.




External connectors



Operating systems


Model SPEC2000, int SPEC2000, fp SPEC2000
rate, int
rate, fp
493 489 5.7
2-CPU: 11.3
4-CPU: 22.1
8-CPU: 42.6
2-CPU: 10.4
4-CPU: 19.3
8-CPU: 30.5
551 524 6.4
2-CPU: 12.5
4-CPU: 24.6
8-CPU: 46.7
2-CPU: 11.0
4-CPU: 20.5
8-CPU: 32.1

Compare these with other results on the Benchmarks page.

Physical dimensions

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