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SMI (Sleep/Resume Switch)
When APM is enabled in the system BIOS, and the operating system's APM driver is loaded, the system can
enter sleep (standby) mode in one of the following ways:
•
Optional front panel SMI button
•
Prolonged system inactivity using the BIOS inactivity timer feature
The 2-pin header located on the front panel I/O connector supports a front panel SMI switch, which must be
a momentary SPST type that is normally open.
Closing the SMI switch sends a System Management Interrupt (SMI) to the processor, which immediately
goes into System Management Mode (SMM).While the computer is in sleep mode it is fully capable of
responding to and servicing external interrupts (such as an incoming fax) even though the monitor turns on
only if a keyboard or mouse interrupt occurs. To reactivate or resume the system, the SMI switch must be
pressed again, or the keyboard or mouse must be used.
Power On Button
This connector can be connected to a front panel power switch. The switch must pull the Power Button pin to
ground for at least 50 ms to signal the power supply to switch on or off. (The time requirement is due to
internal debounce circuitry on the motherboard). At least two seconds must pass before the power supply
will recognize another on/off signal.
1.3.2 ATX 20-pin Power Connector:
This connector supports the power button on-board. Using the ATX power supply, functions such as
Modem Ring Wake-Up and Soft Power Off are supported on this motherboard. This power connector
supports instant power-on functionality, which means that the system will boot up instantly when the power
connector is inserted on the board.
PIN
1
2
3
4
5
6
7
8
9
10
Wa
g S ce t e
a e sta ed p ope y befo e se t g t e powe co
VOLTAGE
PIN
3.3 V
11
12
3.3 V
GND
13
5 V
14
GND
15
5 V
16
GND
17
PW_OK
18
5V_SB
19
12 V
20
ot e boa d as t e sta t powe o f
VOLTAGE
3.3 V
-12 V
GND
PS_ON
GND
GND
GND
-5 V (Optional)
5 V
5 V
ct o ,
a e s e t at a co po
ecto to e s e t at o da age
7
Motherboard Description
ts
e do
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