Intel E7520 User Manual
Dual-Core Intel
®
Xeon
®
processor LV with Intel
®
E7520 Chipset and Intel
®
6300ESB ICH
April 2007
User’s Manual
Order Number: 311274-009
39
Dual-Core Intel Xeon processor LV / E7520 Chipset / 6300ESB ICH
4.2.10
Wake from S5 State
The power button is used to wake from S5.
4.3
PCI PM Support
This design holds the system reset signal low when in a sleep state. The system
supports the PCI PME# signal and provides 3.3 V standby to the PCI and PCI Express
slots. This support allows any compliant PCI or PCI Express card to wake up the system
from any sleep state except mechanical off. Because of the limited amount of power
available on 3.3 V standby, the user and the operating system must configure the
system carefully following the PCI power management interface specification.
4.4
Platform Management
The LM 93 monitors the majority of the system voltages. The VID signals from the
processors are also monitored by LM 93. All voltage levels can be read via the SMBus.
4.4.1
Processor Thermal Management
Each processor monitors its own core temperature and thermally manages itself when
it reaches a certain temperature. The system also uses the internal processor diode to
monitor the die temperature. The diode pins are routed to the diode input pins in the
LM 93. The LM 93 can be programmed to force the processor fans to full speed
operation when it senses the processor core temperature exceeding a specific value. In
addition, the LM 93 has an on-chip thermal monitor which allows it to monitor the
incoming ambient temperature. Additional processor thermal management requires the
system to communicate to the processors when the VRD reaches a critical
temperature. The VR thermal monitor asserts FORCEPR_N signal to the processor.
4.5
System Fan Operation
The system uses both the LM 93 and SMSC LPC47M172 to monitor and control the fans
in the system.The LM93 uses pulse width modulated (PWM) outputs that can modulate
the voltage across the fans, providing a variable duty cycle to effect a reduced DC
voltage from nominal 12V DC.
By default, the CPU fans are jumpered to run at full speed all the time. The fan
headers are the standard 12 V, three-pin type used in previous servers, which support
tachometer out. The LM 93 also has four tachometer inputs that it can use to monitor
the fans it controls. All fan tachometer data can be extracted from the controllers via
the SMBus. The system fan speed control circuit does not control the power supply fan.
Each PWM output has a bypass jumper that causes all fans to run at full speed and
ignore the PWM control. Each processor fan has its own dedicated PWM output and
tachometer input, so each fan is controlled and monitored independently, depending on
the core temperature.
The LM 93 is dedicated to processor fan speed control and monitor, and can be
programmed with temperature limit values that allow it to speed up or idle the
processor fans, depending upon the input temperature.