Intel AC450NX Memory Interface, DC-to-DC Voltage Converters

AC450NX Rack Server System Product Guide
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Memory Interface
The memory subsystem consists of two memory modules installed in the two memory connectors
on the midplane. The memory modules interface with the CPU baseboard through the midplane via
the grand connector. The grand connector provides connectivity between the CPU baseboard, the
PHP I/O baseboard, and memory modules through two 270-pin connectors and one 240-pin
connector.
Each memory module contains sixteen 72-bit wide DIMM sockets that can provide up to 4 GB of
EDO memory per module. The memory bus uses gunning transceiver logic (AGTL)+ signaling
technology. Because the bus must be terminated on each end, both memory connectors must
contain a memory module; however, only one memory module must be populated with memory.
DC-to-DC Voltage Converters
The plug-in VRM8.3 DC to DC converters, on the CPU baseboard, supply voltage for the
processors and the L2 caches. All the converters convert off the +12 V supply rail.
• Four converters supply voltage for the four processor cores.
• Two converters supply voltage for the four processor L2 caches (two L2 caches share one
converter).
An onboard switching converter provides the 1.5 V AGTL+ termination voltage (VTT) required by
the CPU baseboard, memory modules, and processors. A second onboard linear converter
provides +2.5 V for the logic on the CPU baseboard (clock buffers and voltage shifters). Both
converters use the +5 V supply rail as source voltage.
DS1624 SEEPROM
When the DS1624 on the CPU baseboard is accessed via the I2C bus, it provides a temperature
reading of the ambient temperature of the CPU baseboard. The DS1624 also provides:
• time and date the CPU baseboard was manufactured
• name of the board manufacturer
• name and description of the board
• serial number of the board
• part number of the board