Detaching CMOS Battery

• 1). Turn off the computer and unplug it from the wall outlet. If you are using a laptop, remove the battery pack from its bay under the device. Disconnect any devices, such as printers, scanners, routers or modems, from the computer.
  
  
• 2). Remove the CMOS battery. Doing so will erase all information stored in the CMOS and clear the BIOS, including any stored passwords. Locate a flat circular component (resembling a watch battery) inserted on a slot in the motherboard, and gently pry it loose. Locating and removing the CMOS battery may be a more involved process for laptop computers, owing to its intricate arrangement. Refer to your documentation for location of the CMOS battery, and any removal instructions. You may or may not have to disassemble the laptop, depending on laptop make and model.
  
  
• 3). Reattach the battery after 30 minutes. Reassemble the computer by putting the tower casing back together (for desktops) or following manufacturer recommended procedures (for laptops). Turn on the computer and hit "F1" when you see this message: "CMOS checksum error." Navigate through the BIOS Settings interface and apply a new password or load default settings.
  
  

Changing CMOS Jumper Setting

• 1). Turn off the computer and unplug its power cord. Detach all components from the computer with a live power source. Lay the desktop's tower casing on its side and unscrew one of its walls to access the CMOS jumper in the motherboard. For a laptop, refer to documentation for instructions on accessing the CMOS jumper.
  
  
• 2). Identify the CMOS jumper attached to the motherboard. If you are unsure, look for a small rectangular component, usually black, adjacent to the CMOS battery. The jumper may or may not be labeled.
  
  
• 3). Set the jumper to its "clear" position. Refer to your motherboard's architecture to learn which position will change its setting to "clear." This will clear the BIOS and all information stored in the CMOS. Reassemble the computer and power it up.
  
  
• 4). Press "F1" when the "CMOS checksum error" message displays and apply a new BIOS password.