IBM Intel Xeon E5506 46M1079 User Manual
Product codes
46M1079
Intel
®
Xeon
®
Processor 5500 Series Datasheet, Volume 1
127
Thermal Specifications
6.3.6
Temperature Data
6.3.6.1
Format
The temperature is formatted in a 16-bit, 2’s complement value representing a number
of 1/64 degrees centigrade. This format allows temperatures in a range of ±512°C to
be reported to approximately a 0.016°C resolution.
of 1/64 degrees centigrade. This format allows temperatures in a range of ±512°C to
be reported to approximately a 0.016°C resolution.
6.3.6.2
Interpretation
The resolution of the processor’s Digital Thermal Sensor (DTS) is approximately 1°C,
which can be confirmed by a RDMSR from IA32_THERM_STATUS MSR (0x19C) where it
is architecturally defined. PECI temperatures are sent through a configurable low-pass
filter prior to delivery in the GetTemp() response data. The output of this filter produces
temperatures at the full 1/64°C resolution even though the DTS itself is not this
accurate.
which can be confirmed by a RDMSR from IA32_THERM_STATUS MSR (0x19C) where it
is architecturally defined. PECI temperatures are sent through a configurable low-pass
filter prior to delivery in the GetTemp() response data. The output of this filter produces
temperatures at the full 1/64°C resolution even though the DTS itself is not this
accurate.
Temperature readings from the processor are always negative in a 2’s complement
format, and imply an offset from the reference TCC activation temperature. As an
example, assume that the TCC activation temperature reference is 100°C. A PECI
thermal reading of -10 indicates that the processor is running approximately 10°C
below the TCC activation temperature, or 90°C. PECI temperature readings are not
reliable at temperatures above TCC activation (since the processor is operating out of
specification at this temperature). Therefore, the readings are never positive.
format, and imply an offset from the reference TCC activation temperature. As an
example, assume that the TCC activation temperature reference is 100°C. A PECI
thermal reading of -10 indicates that the processor is running approximately 10°C
below the TCC activation temperature, or 90°C. PECI temperature readings are not
reliable at temperatures above TCC activation (since the processor is operating out of
specification at this temperature). Therefore, the readings are never positive.
6.3.6.3
Temperature Filtering
The processor digital thermal sensor (DTS) provides an improved capability to monitor
device hot spots, which inherently leads to more varying temperature readings over
short time intervals. Coupled with the fact that typical fan speed controllers may only
read temperatures at 4 Hz, it is necessary for the thermal readings to reflect thermal
trends and not instantaneous readings. Therefore, PECI supports a configurable low-
pass temperature filtering function. By default, this filter results in a thermal reading
that is a moving average of 256 samples taken at approximately 1msec intervals. This
filter’s depth, or smoothing factor, may be configured to between 1 sample and 1024
samples, in powers of 2. See the equation below for reference where the configurable
variable is ‘X’.
device hot spots, which inherently leads to more varying temperature readings over
short time intervals. Coupled with the fact that typical fan speed controllers may only
read temperatures at 4 Hz, it is necessary for the thermal readings to reflect thermal
trends and not instantaneous readings. Therefore, PECI supports a configurable low-
pass temperature filtering function. By default, this filter results in a thermal reading
that is a moving average of 256 samples taken at approximately 1msec intervals. This
filter’s depth, or smoothing factor, may be configured to between 1 sample and 1024
samples, in powers of 2. See the equation below for reference where the configurable
variable is ‘X’.
T
N
= T
N-1
+ 1/2
X
* (T
SAMPLE
- T
N-1
)
Please refer to
command.
Figure 6-26. Temperature Sensor Data Format
MSB
Upper nibble
Upper nibble
MSB
Lower nibble
Lower nibble
LSB
Upper nibble
Upper nibble
LSB
Lower nibble
Lower nibble
S
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Sign
Integer Value (0-511)
Fractional Value (~0.016)