64-bit Intel Xeon Processorwith up to 8MB L3 Cache Thermal/Mechanical Design Guidelines

Thermal/Mechanical Reference Design
R
12 64-bit Intel
®
Xeon™ Processor MP with 8 MB L3 Cache
Thermal/Mechanical Design Guidelines
Where:
y = Processor case temperature, T
CASE
(°C)
x = Processor power consumption (W)
a = Case-to-ambient thermal resistance, Ψ
CA
(°C/W)
b = Processor local ambient temperature, T
LA
(°C)
Figure 2-3. Thermal Profile Diagram
Pcontrol_Base TDP
T
CASE
MAX
Power
Thermal Profile
@Pcontrol_Base
T
CASE
MAX
T
CASE
T
CASE
MAX @
Pcontrol_base
T
CASE
MAX
Pcontrol_Base TDP
T
CASE
MAX
Power
Thermal Profile
@Pcontrol_Base
T
CASE
MAX
T
CASE
T
CASE
MAX @
Pcontrol_base
T
CASE
MAX
The higher end point of the Thermal Profile represents the processor’s TDP and the associated
maximum case temperature (T
CASE
MAX). The lower end point of the Thermal Profile represents the
power value (Pcontrol_base) and the associated case temperature (T
CASE
MAX@Pcontrol_base) for
the lowest possible theoretical value of T
CONTROL
(see Section 2.2.3). This point is also associated
with the T
CONTROL
value defined in Section 2.2.2. The slope of the Thermal Profile line represents
the case-to-ambient resistance of the thermal solution with the y-intercept being the local processor
ambient temperature. The slope of the Thermal Profile is constant between P
CONTROL BASE
and TDP,
which indicate that all frequencies of a processor defined by the Thermal Profile, will require the
same heatsink case-to-ambient resistance.
In order to satisfy the Thermal Profile specification, a thermal solution must be at or below the
Thermal Profile line for the given processor when its diode temperature is greater than T
CONTROL
(refer to Section 2.2.2). The Thermal Profile allows the customers to make a trade-off between the
thermal solution case-to-ambient resistance and the processor local ambient temperature that best
suits their platform implementation (refer to Section 2.3.3). There can be multiple combinations of
thermal solution case-to-ambient resistance and processor local ambient temperature that can meet a
given Thermal Profile. If the case-to-ambient resistance and the local ambient temperature are
known for a specific thermal solution, the Thermal Profile of that solution can easily be plotted
against the Thermal Profile specification. As explained above, the case-to-ambient resistance
represents the slope of the line and the processor local ambient temperature represents the y-axis
intercept. Hence, the T
CASE
values of a specific solution can be calculated at the TDP and
Pcontrol_base power levels. Once these points are determined, they can be joined by a line, which
represents the Thermal Profile of the specific solution. If that line stays at or below the Thermal
Profile specification, then that particular solution is deemed as a compliant solution.