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Chapter 4: Motherboard Connections
4.3 Jumpers
Explanation of Jumpers
To modify the operation of the motherboard, jumpers can be used to choose between optional
settings. Jumpers create shorts between two pins to change the function of the connector.
Pin 1 is identified with a square solder pad on the printed circuit board. See the diagram
below for an example of jumping pins 1 and 2. Refer to the motherboard layout page for
jumper locations.
Note:
On two-pin jumpers, Closed means the jumper is on the pins and Open means the
jumper is off.
Connector
Pins
Jumper
Setting
3 2 1
3 2 1
CMOS Clear
JBT1 is used to clear the CMOS, which will also clear any passwords.. Instead of pins, this
jumper consists of contact pads to prevent accidental clearing of the CMOS.
Note:
Shut down the system and then short JBT1 to clear the CMOS.
To Clear CMOS
1. First power down the system and unplug the power cord(s).
2. Remove the cover of the chassis to access the motherboard.
3. Remove the onboard battery from the motherboard.
4.
Short the CMOS pads with a metal object such as a small screwdriver for at least four
seconds.
5. Remove the screwdriver (or shorting device).
6. Replace the cover, reconnect the power cord(s), and power on the system.
Note:
Clearing CMOS will also clear all passwords.
Do not use the PW_ON connector to clear CMOS.
JBT1 contact pads
