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P H 4 4 0 N L X M o t h e r b o a r d U s e r G u i d e
SYSTEM MANAGEMENT
There are three main elements to the system management hardware.
A Heceta II system monitor
The PIIX4e power management devices 9 and 10
Processor thermal diode ADCs
Heceta II System Monitor
The Heceta II provides the system monitor functions as described below and is accessed via the
PIIX4e SMbus interface. It provides the following functions.
Fan monitoring. The two inputs to the Heceta II device monitor the first two NLX
"fantach" signals.
Monitoring of system +12V, +5V, +3.3V, CPU core, -12V and 2.5V power rails
Monitoring of system temperature (actually the motherboard surface temperature)
Monitoring of chassis intrusion (top cover)
FAN CONTROL
The NLX system fan is controlled by the motherboard such that it stops rotating when the system
is in 'Suspend' mode. As a build option, the PH440 NLX motherboard supports variable fan
speed control in which the speed of the fan is raised as the temperature of the processor
increases. This considerably reduces fan noise in normal operation.
The variable fan speed option can only be used with an ACPI-aware operating system (such as
Windows 98) and a 100MHz-bus Pentium® II processor.
EXPANSION SLOTS
The ISA and PCI expansion slots are located on the riser card. The ISA and PCI signals are
routed through an edge connector on one edge of the board which mates with the NLX riser.
As per the NLX specification, the motherboard requires that the PCI signals are correctly
terminated and pulled up on the NLX riser for the motherboard to operate properly.
Industry Standard Architecture (ISA)
A maximum of 5 ISA slots is supported via the NLX riser.
Peripheral Component Interconnect (PCI)
A maximum of 4 PCI cards is supported via the NLX riser, each with bus master support.
MITSUBISHI ELECTRIC MOTHERBOARD DIVISION
S e p t e m b e r 1 9 9 8
PAGE 26 OF 51
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