Intel 820E Benutzerhandbuch

Design Guide 

 

183 

Suspend to 

RAM (STR) 

In the STR state, the system state is stored in main memory and all unnecessary 

system logic is turned off. Only main memory and logic required to wake the 

system remain powered. This state is used in the Customer Reference Board to 

satisfy the S3 ACPI power management state. 

Full-power 

operation 

During full-power operation, all components on the motherboard remain powered. 

Note that full-power operation includes both the full-on operating state and the S1 

(

processor

 Stop Grant state) state. 

Suspend 

operation 

During suspend operation, power is removed from some components on the 

motherboard. The customer reference board supports two suspend states: Suspend 

to RAM (S3) and Soft-Off (S5). 

Power rails 

An ATX power supply has 6 power rails: +5 V, -5 V, +12 V, -12 V, +3.3 V, and 

5 V

SB

. In addition to these power rails, several other power rails are created with 

voltage regulators on the Intel 820E chipset reference board.  

Core power rail  These power rails are on only during full-power operation. These power rails are on 

when the PSON signal is asserted to the ATX power supply. The following core 

power rails are distributed directly from the ATX power supply: ±5 V, ±12 V, and 

+3.3 V. 

Standby power 

rail 

These power rails are on during the suspend operation. (These rails also are on 

during full-power operation.) These rails are on at all times (when the power supply 

is plugged into AC power). The only standby power rail that is distributed directly 

from the ATX power supply is 5 V

SB

 (5 V standby). Other standby rails are created 

with voltage regulators on the motherboard. 

Derived power 

rail 

A derived power rail is any power rail generated from another power rail using an 

on-board voltage regulator. For example, 3.3 V

SB

 usually is derived (on the 

motherboard) from 5 V

SB

 using a voltage regulator. (On the Intel 820E chipset 

reference board, 3.3 V

SB

 is derived from 5V_DUAL.) 

Dual power rail  A dual power rail is derived from different rails at different times (depending on the 

power state of the system). Usually, a dual power rail is derived from a standby 

supply during the suspend operation and is derived from a core supply during full-

power operation. Note that the voltage on a dual power rail may be misleading.