Dell PowerEdge T20 Technical Guide - Page 19

7 Power, thermal and acoustics Lower overall system-level power draw is a result of breakthrough system design. The Dell PowerEdge T20 server maximizes performance per watt through a combination of power and cooling, energy-efficient technologies and tools. Additionally, the PowerEdge T20 has an extensive collection of sensors that automatically track thermal activity, which helps regulate temperature, thereby reducing server noise and power consumption. Power management Table 14 summarizes power management features on the PowerEdge T20. Table 14. Power management features Feature Type Enable/Status/Ctrl bit location Description ACPI mode switch Sleep states Fixed Fixed Power button Fixed Real-time clock (RTC) Fixed Power management timer Fixed Power management event (PME) Generic DBS N/A C state support N/A PCH PCH PCH PCH PCH PCH Processor MSRs Processor and PCH registers The operating system uses the SCI_EN bit in PCH to switch from legacy mode to ACPI mode. Supported states: S0 (Working), S4-OS ('Hibernation'), and S5 (Soft-off). S1 (also called 'standby' or 'suspend') and S3 are not supported. In ACPI mode, the operating system has control of the power button. In non-ACPI mode, SMI handler owns power button events. The operating system is able to configure the system to wake on the RTC alarm. PCH 32-bit power management timer is used. When a device signals PME, the system wakes (if necessary), the OS detects the event, and a Delldefined ASL routine handles the event. Wake-on-LAN is one example of a PME. This feature does P state transition under Windows. This feature allows multiple C state support for the processor. This feature will work under Windows and ACPI OS that understand C states. Dell PowerEdge T20 Technical Guide 18