How do I clear the CMOS (manually reset the BIOS) on my PC?

If your system fails to POST (powers on but never proceeds to the boot process), you may need to clear your CMOS.

Depending on the motherboard make/manufacturer (and sometimes even the model) the steps are generally the same, but can differ slightly. Also note that removal of other hardware (video card, audio card, etc.) may be requried to access the CMOS battery or jumper.

THE NORMAL STEPS ARE AS FOLLOWS:

Applies to most Asus, MSI, FoxConn, PNY, XFX, and Intel motherboards older than 2005

  • Power off and unplug power cord from rear of system (also unplug any powered USB hubs.
  • Remove the side panel, locate and remove the CMOS battery.
  • Locate the BIOS configuration jumper for your motherboard (often very close to the battery, refer to your manual for additional information) and move the jumper from pins 1 & 2 to pins 2 & 3.
  • After ~5-10 seconds, move the jumper back to the original pins.
  • Return the battery to it's socket (positive side facing out).
  • Replug the power cord to the power supply on the rear.

BELOW ARE EXAMPLES OF DEVIATIONS FROM THE ABOVE NORM:

Applies to most EVGA motherboards:

  • Power off and unplug power cord from rear of system (also unplug any powered USB hubs).
  • Remove the side panel.
  • Locate the BIOS configuration jumper for your motherboard (often very close to the battery, refer to your manual for additional information) and move the jumper from pins 1 & 2 to pins 2 & 3.
  • After ~5-10 seconds, move the jumper back to the original pins.
  • Replug the power cord to the power supply on the rear.

Applies to most Intel motherboards newer than 2005:

  • Power off system and remove the side panel.
  • Locate the BIOS configuration jumper for your motherboard (often very close to the battery, refer to your manual for additional information) and move the jumper from pins 1 & 2 to pins 2 & 3.
  • Power system on, the display should show the BIOS MAINTENANCE MENU.
  • Navigate to the option to LOAD SETUP DEFAULTS and press ENTER.
  • Press F10 to EXIT SAVING CHANGES.
  • Move the jumper back to the original pins.

Applies to some EVGA (ie X58) and MSI (ie P7N) motherboards:
These motherboards are equipped with a button that will clear the CMOS for you, eliminating the need for removing a battery or moving jumpers. This button may be a small red button on the rear of the case or on the bottom of the motherboard, or a small square backlit button on the bottom of the motherboard usually labelled "CLR CMOS".

  • While not necessary to unplug the power cord from rear of system (only powering off is required), we advise you do so anyway to ensure all power is off (also unplug any powered USB hubs).
  • Refer to your motherboard manual to locate the CLR CMOS button (remove the side panel if required) and press for ~5-10 seconds.
  • Replug the power cord to the power supply on the rear.

Applies to Intel P55 chipset based motherboards

  • Power off system and remove power cord and side panel.
  • With most models the video card will need to be removed as it is blocking the jumper (be sure to disconnect the power leading to the video card as well).
  • Locate the BIOS configuration jumper for your motherboard (this jumper is beige and about 3/8ths of an inch long, refer to your manual for additional information) and move the jumper from pins 1 & 2 to pins 2 & 3.
  • Plug in and power on the computer.
  • Once the fans spin down a bit (about 10 to 15 seconds), power off the system and remove the power cord.
  • Move the jumper back to the original pins, reinsert the video card and power cables.
  • Replug the power cord to the power supply on the rear.

AFTER CLEARING CMOS:

Having done the above, turn PC on and wait for CMOS CHECKSUM ERROR (this is normal and expected). From here you may either be told that DEFAULTS have been LOADED, or prompted to press F1 to load Defaults or DEL to enter BIOS SETUP PROGRAM. You will need to enter the BIOS to make changes as required.

This may include:

  • Disabling onboard audio in deference for an add-in card.
  • Enabling RAID as the default setting is often "DISABLED".
  • Adjusting memory timings and voltages.
  • Restoring any overclock settings.

Once in Windows, the PC's time and date may also need to be corrected.