Intel Phi 7120A SC7120A Data Sheet

Intel

®

 Xeon Phi™ Coprocessor Datasheet

Document ID Number: 328209 003EN

18

Thermal management on the Intel® Xeon Phi™ coprocessor card is achieved through a 
combination of coprocessor based sensors, card level sensors and inputs, and a 
coprocessor frequency control circuit. Reducing card temperature is accomplished by 
adjusting the frequency of the coprocessor. Lowering the coprocessor frequency will 
reduce the power dissipation and consequently the temperature.

The coprocessor carries in it a factory calibrated Digital Temperature Sensor (DTS) that 
monitors coprocessor temperature, also called junction temperature (T

junction

). Data 

from this sensor is available to the BMC or other system software via both in-band 
(direct software reads) and out-of-band (over the PCI Express* SMBus) interface. Refer 
to chapter titled “Manageability” for more information on how to read the junction 
temperature. System management software can use this data to monitor the silicon 
temperature and take any appropriate actions. Systems that adjust airflow based on 
component temperatures must monitor the coprocessor’s DTS to ensure sufficient 
cooling is always available.

In addition to making thermal information available to system manageability software, 
the DTS is constantly comparing the coprocessor temperature to the factory set 
maximum permissible temperature called T

throttle

. If the measured temperature at any 

time exceeds T

throttle 

(a state also known as PROCHOT), then the coprocessor will 

automatically step down the operating frequency (or Pstate) in an attempt to reduce 
the temperature (this is often referred to as “thermal throttling”). Once the 
temperature has dropped below T

throttle

, the frequency will be brought back up to the 

original setting. See 

 below.

T

RISE

10°C

Max T

INLET

45°C

Max T

EXHAUST

70°C

T

case (processor) 

min, max

5°C, 95°C

T

control

~82°C

1

1. T

control 

is the setpoint at which the system fans must ramp up towards full power (or RPM) to maintain the

Intel® Xeon Phi™ coprocessor temperature around T

control 

and prevent throttling. It is a requirement that

the system BMC use IPMB commands to query the SMC on the coprocessor card for accurate T

control

 value

as this value can vary between 80

°C

 and 84

°C

.

T

throttle

104°C

2

2. When the coprocessor junction temperature (T

junction

) reaches T

throttle

, the SMC will force thermal throttle

which will drop frequency to lowest supported value and reduce total coprocessor power. It is a requirement

that the system BMC query the SMC on the coprocessor card for accurate 

T

throttle 

value.

T

thermtrip

~(T

throttle

 + 20°C)

3

3. If the coprocessor temperature reaches T

thermtrip

, the coprocessor OS will take action to shutdown the card

to prevent damage to the coprocessor. This includes shutting down the coprocessor VRs, and the only way

to restart the coprocessor is by rebooting the host system. T

thermtrip

 should not be considered a

specification; it can change between SKUs, and is given here as guidance.