Vol 1

Electrical Specifications
70 Intel® Xeon® Product 2800/4800/8800 v2 Product Family
Datasheet Volume One, February 2014
6.1.5 Platform Environmental Control Interface (PECI)
PECI is an Intel proprietary interface that provides a communication channel between
Intel processors and chipset components to external system management logic and
thermal monitoring devices. The Intel® Xeon® E7 v2 processor contains a Digital
Thermal Sensor (DTS) that reports a relative die temperature as an offset from
Thermal Control Circuit (TCC) activation temperature. Temperature sensors located
throughout the die are implemented as analog-to-digital converters calibrated at the
factory. PECI provides an interface for external devices to read processor temperature,
perform processor manageability functions, and manage processor interface tuning
and diagnostics.
6.1.5.1 Input Device Hysteresis
The PECI client and host input buffers must use a Schmitt-triggered input design for
improved noise immunity. Please refer to Figure 6-1 and Table 6-20.
6.1.6 System Reference Clocks (BCLK{0/1}_DP,
BCLK{0/1}_DN)
The processor core, processor uncore, Intel® QuickPath Interconnect link, PCI
Express* and VMSE memory interface frequencies) are generated from BCLK{0/1}_DP
and BCLK{0/1}_DN signals. There is no direct link between core frequency and Intel
QuickPath Interconnect link frequency (for example, no core frequency to Intel
QuickPath Interconnect multiplier). The processor maximum core frequency, Intel
QuickPath Interconnect link frequency and DDR memory frequency are set during
manufacturing. It is possible to override the processor core frequency setting using
software. This permits operation at lower core frequencies than the factory set
maximum core frequency.
The processor core frequency is configured during reset by using values stored within
the device during manufacturing. The stored value sets the lowest core multiplier at
which the particular processor can operate. If higher speeds are desired, the
appropriate ratio can be configured via the IA32_PERF_CTL MSR (MSR 199h);
Bits [15:0].
Figure 6-1. Input Device Hysteresis
Minimum V
P
Maximum V
P
Minimum V
N
Maximum V
N
PECI High Range
PECI Low Range
Valid Input
Signal Range
Mi ni mum
Hysteresis
V
TTD
PECI Ground