Intel E7-8891 v2 CM8063601377422 User Manual

Product codes
Page of 504
Processor E7-2800/4800/8800 v2 Product Family
Datasheet Volume Two: Functional Description, February 2014
PCU Functional Description
— Note that platform ‘power’ management includes monitoring and 
control for both the processor and DRAM subsystem to assist with data center 
power limiting.
Thermal Management
Processor fan speed control is managed by comparing Digital Thermal Sensor (DTS) 
thermal readings acquired via PECI against the processor-specific fan speed control 
reference point, or T
. Both T
 and DTS thermal readings are accessible 
via the processor PECI client. 
PECI-based access to the processor package configuration space provides a means for 
Baseboard Management Controllers (BMCs) or other platform management devices to 
actively manage the processor and memory power and thermal features.
Platform Manageability
PECI allows read access to certain error registers in the processor MSR space and 
status monitoring registers in the PCI configuration space within the processor and 
downstream devices. 
PECI permits writes to certain Memory Controller RAS-related registers in the processor 
PCI configuration space. 
Platform Power Limits (RAPL)
Every platform is designed to meet the specifications of the CPU’s in the platform. Each 
CPU requires a specific amount of electrical power and cooling capability. There are two 
distinct classes of specification, electrical and thermal. The electrical parameters 
pertain to the design of power delivery, specifically the sizing of the VRs, capacitors, 
etc. The thermal parameters refer to the design of the cooling system. 
• EDP - Electrical design parameters for example ICCMax, Itdp, Voltage, AC load-line, 
DC load-line, and so forth.
• TDP - Thermal Design Power - maximum amount of the heat that can be dissipated 
by the cooling system without exceeding maximum junction temperature. (AES-
256 excluded).
During normal operation, processor can increase its voltage and frequency as long 
as it stays below the EDP and TDP specifications of the platform.
ACPI P-States
In ACPI terminology, a P-state is a software visible frequency / voltage operating point. 
The OS, BIOS or any ring 0 software has the permissions to make P-state change 
requests. In the Intel Xeon processor E7 v2 product family processor, P-state targets 
correspond to the core clock ratio that is requested. 
Turbo Modes
The past frequency definition has a nominal (or guaranteed) frequency of a processor. 
When all cores are executing a TDP workload, the power of the processor will be less 
than or equal to the TDP spec at the nominal frequency and associated voltage. The 
OEM should design a thermal solution to cool the TDP power of the processor at any 
time. This cooling needs to assume worse case ambient temperature, heavy platform 
load and worse case tolerance of power delivery and cooling components. There are 
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