CMOS stands for Complementary metal--oxide--semiconductor and is a type of microprocessor that is used to store a computer's basic input/output system, or BIOS. The BIOS is a small set of instructions designed to get the computer up and running and to load the operating system. Clearing the CMOS will return all BIOS settings to their defaults. This can be useful when diagnosing computer problems. The Dell Inspiron 531 desktop computer contains a clear CMOS jumper on the motherboard that will allow you to easily clear the BIOS settings.
- Skill level:
- Moderately Easy
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Things you need
- Anti-static wrist strap
- Small flat-blade screwdriver
- Needle-nose pliers
Prepare the computer for service by first shutting it down and then disconnecting the power cable and all peripheral devices attached to the computer.
Place the computer onto its left side as you face it from the rear.
Use a flat-blade screwdriver to remove the two screws from the rear of the case that hold the cover on. Pull the cover toward the rear of the case a few inches and then lift it off the case to expose the motherboard and other internal components.
Attach your anti-static wrist strap. Make sure you attach the clip to an unpainted metal surface on the computer chassis. This will ground you and prevent a static electric discharge which can damage sensitive computer parts like the RAM modules and processor.
Locate the jumper located along the edge of the motherboard furthest from you as you face the rear of the computer. It has two rows of three pins each. The clear CMOS jumper is the set of three pins closest to the rear of the computer.
Remove the jumper from its current position on pins one and two and place it onto pins two and three. Wait approximately five minutes for the CMOS to clear and replace the jumper onto pins one and two. The CMOS settings are now reset to the defaults.
Tips and warnings
- If you cant grasp the jumper connector with your fingers, use a pair of needle-nose pliers.
- Make sure you protect the computer against electrostatic discharge damage by wearing an anti-static wrist strap attached to the computer's chassis.
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