Guide

Introduction
12 Intel® Xeon® Processor E7 2800/4800/8800 v2 Product Family
Thermal/ Mechanical Specifications and Design Guide
1.4 Terminology
Table 1-2. Terms and Descriptions
Term Description
Bypass Bypass is the area between a passive heatsink and any object that can act to form a
duct. For this example, it can be expressed as a dimension away from the outside
dimension of the fins to the nearest surface.
DTS Digital Thermal Sensor reports a relative die temperature as an offset from TCC
activation temperature.
FSC Fan Speed Control
HTg Printed circuit board material, such as FR4, with high glass transition temperature
IHS Integrated Heat Spreader: a component of the processor package used to enhance the
thermal performance of the package. Component thermal solutions interface with the
processor at the IHS surface.
ILM Independent Loading Mechanism - Provides the force required to seat the 2011-Land
FCLGA package onto the socket to maintain the interface between the processor and the
socket.
LGA2011-1 Socket Surface mounted socket with 2011-contacts enabling the processor to interface with the
system board.
Pad Crater Mechanically induced fracture in the resin between copper foil and outermost layer of
fiberglass of a printed circuit board
PECI The Platform Environment Control Interface (PECI) is a one-wire interface that provides
a communication channel between Intel processor and chipset components to external
monitoring devices.
Ψ
CA
Case-to-ambient thermal characterization parameter. A measure of thermal solution
performance. Defined as (T
CASE
– T
LA
) / Total Package Power. Heat source should always
be specified for Ψ measurements.
Ψ
CS
Case-to-sink thermal characterization parameter. A measure of thermal interface
material performance. Defined as (T
CASE
– T
S
) / Total Package Power.
Ψ
SA
Sink-to-ambient thermal characterization parameter. A measure of heatsink thermal
performance using total package power. Defined as (T
S
– T
LA
) / Total Package Power.
T
CASE
The case temperature of the processor measured at the geometric center of the topside
of the IHS.
T
CASE
_
MAX
The maximum case temperature as specified in a component specification.
TCC Thermal Control Circuit: Thermal monitor uses the TCC to reduce the die temperature
by using clock modulation and/or operating frequency and input voltage adjustment
when the die temperature is very near its operating limits.
T
CONTROL
T
CONTROL
is a static value below TCC activation used as a trigger point for fan speed
control. When DTS > T
CONTROL
, the processor must comply to the thermal profile.
TDP Thermal Design Power: Thermal solution should be designed to dissipate this target
power level. TDP is not the maximum power that the processor can dissipate.
Thermal Monitor A power reduction feature designed to decrease temperature after the processor has
reached its maximum operating temperature.
Thermal Profile Line that defines case temperature specification of a processor at a given power level.
TIM Thermal Interface Material: The thermally conductive compound between the heatsink
and the processor case. This material fills the air gaps and voids, and enhances the
transfer of the heat from the processor case to the heatsink.
T
LA
The measured ambient temperature locally surrounding the processor. The ambient
temperature should be measured just upstream of a passive heatsink or at the fan inlet
for an active heatsink.
T
SA
The system ambient air temperature external to a system chassis. This temperature is
usually measured at the chassis air inlets.
U A unit of measure used to define server rack spacing height. 1U is equal to 1.75 in, 2U
equals 3.50 in, and so forth.