NEC EXPRESS 320Lb User Manual page 21

As application requirements increase, you can expand your server with additional
processors, additional memory, add-in boards and peripheral devices.
Your server features the following major components:
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Up to two high-performance Xeon 2.4GB processors in each CPU module.
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Up to 3 GB of Synchronous Dynamic Random-Access (SDRAM) system memory in
each CPU module.
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Three PCI expansion slots, which support one 32-bit/33Mhz and two 64-bit/33Mhz
PCI adapter cards in each PCI module. One of the PCI expansion slots in each PCI
module contains a graphics board.
Fault-Tolerant Hardware
The hardware architecture of the system provides fault tolerance transparency. If a
hardware component fails, the application program continues processing and is never
aware that a failure occurred.
To provide system redundancy this system uses dual hardware technology. That means
that all major components are mirrored within a single hardware chassis. There are two
CPU modules and each CPU module is operating in lockstep (performing the same
instructions at the same time) with the other as a single system. Thus, if a failure occurs
in one CPU module the other CPU module will continue to operate with no
interruption, no loss of data, and system performance is not affected. Note that the PCI
module, PCI adapters, and power supplies are also paired for system redundancy.
1-4 System Overview