Intel Xeon Processor E5-1600 Datasheet page 77

Temperature readings from the processor are always negative in a 2's complement
format, and imply an offset from the processor T
processor T
running at approximately 10°C below T
not reliable at temperatures above T
range and hence, PECI temperature readings are never positive.
The changes in PECI data counts are approximately linear in relation to changes in
temperature in degrees centigrade. A change of '1' in the PECI count represents
roughly a temperature change of 1 degree centigrade. This linearity is approximate and
cannot be guaranteed over the entire range of PECI temperatures, especially as the
offset from the maximum PECI temperature (zero) increases.
2.5.7.3 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 4Hz, 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 that is expressed by the equation:
T = (1-
N
T
where
N
respectively,
' ' = 1/2
described in
2.5.7.4 Reserved Values
Several values well out of the operational range are reserved to signal temperature
sensor errors. These are summarized in
Table 2-24. Error Codes and Descriptions
Error Code
0x8000
0x8001
0x8002
0x8003-0x81ff
Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families
Datasheet Volume One
is 100°C, a PECI thermal reading of -10 implies that the processor is
jmax
* T + * T
N-1 SAMPLE
T
and are the current and previous averaged PECI temperature values
N-1
T
is the current PECI temperature sample value and the variable
SAMPLE
X
, where 'X' is the 'Thermal Averaging Constant' that is programmable as
Section 2.5.2.6.21.
General Sensor Error (GSE)
Reserved
Sensor is operational, but has detected a temperature below its operational range
(underflow)
Reserved
(PECI = 0). For example, if the
jmax
or at 90°C. PECI temperature readings are
jmax
since the processor is outside its operating
jmax
Table 2-24.
Description
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