Vol 1

Signal Descriptions
68 Intel® Xeon® Product 2800/4800/8800 v2 Product Family
Datasheet Volume One, February 2014
5.11 Processor Power and Ground Supplies
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RSVD RESERVED. All signals that are RSVD must be left unconnected on the board.
SKTOCC_N SKTOCC_N (Socket occupied) will be pulled to ground in the processor package to
indicate that the processor is present. There is no connection to the processor
silicon for this signal. 4.7kW pull-up to 3.3V
SOCKET_ID[2:0] Socket identification configuration straps for establishing the PECI address, Intel®
QPI Node ID, and other settings. Each processor socket consumes one Node ID,
and there are 128 Home Agent tracker entries.
TEST[13:0] Test[13:0] must be individually connected to an appropriate power source or
ground through a resistor for proper processor operation.
TXT_AGENT Indicates the Intel® Trusted Execution Technology (Intel® TXT) Agent. This
feature is disabled by default via internal pull-down resistor. Strap to VCCIO on the
legacy socket only via 240 Ohm resistor to enable the feature.
TXT_PLTEN Intel® TXT disable. This feature is enabled by default via an internal pull-up
resistor. Strap to 0 on all sockets to disable the feature. Use a zero ohm resistor if
future flexibility is desirable.
Table 5-12. Power and Ground Signals
Signal Name Description
VCC Variable power supply for the processor cores, last level caches (LLC), ring interface, and
home agent. It is provided by a VRM/EVRD12.5 compliant regulator for each CPU socket.
The valid voltage of this supply is indicated by the processor using the serial voltage ID
(SVID) interface.
VCC_SENSE
VSS_VCC_SENSE
VCC_SENSE and VSS_VCC_SENSE provide an isolated, low impedance connection to the
processor core power and ground. These signals must be connected to the voltage
regulator feedback circuit, which insures the output voltage (that is, processor voltage)
remains within specification.
VCC33 VCC33 supplies 3.3 V to PIROM/OEM Scratch ROM. This supply is required for PIROM
usage.
VCCIO_IN Next generation processor only power supply
VCCPLL Fixed power supply (1.8 V) for the processor phased lock loop (PLL). Also known as
VCCsfr
VTTA and VTTQ Combined fixed analog and quiet analog supply for VMSE, Power Control Unit (PCU),
miscellaneous IO, Direct Media Interface Gen 2 (DMI2) interface, Intel QPI interface and
PCI Express* interface at VTT voltage (1.0 V). Also known as VCCio
VTT_SENSE
VSS_VTT_SENSE
VTT_SENSE and VSS_VTT_SENSE provide an isolated, low impedance connection to the
processor I/O power plane. These signals must be connected to the voltage regulator
feedback circuit, which insures the output voltage (that is, processor voltage) remains
within specification.
VCCPECI Power supply for PECI. Next generation processors only.
VSA Variable power supply for the processor system agent units. These include logic (non-
I/O) for the integrated I/O controller, the integrated memory controller (iMC), and the
Intel QPI agent.
VSA_SENSE
VSS_VSA_SENSE
VSA_SENSE and VSS_VSA_SENSE provide an isolated, low impedance connection to the
processor system agent (VSA) power plane. These signals must be connected to the
voltage regulator feedback circuit, which insures the output voltage (that is, processor
voltage) remains within specification.
VSS Processor ground node.
VVMSE01 and
VVMSE23
1.35 volt power supply for the processor system memory interface. VVMSE is generic for
VVMSE01, VVMSE23.
Note: The processor must be provided VVMSE011 and VVMSE23 for proper operation,
even in configurations where no memory is populated.
Table 5-11. Miscellaneous Signals (Sheet 2 of 2)
Signal Name Description