How can I reset CMOS or BIOS settings?

If your computer is having issues booting, has errors during boot, after adding hardware is running into issues, or you're having other abnormal system behaviors that cannot be resolved though any other method it may be necessary to reset the CMOS settings or load the default or fail-safe defaults as explained below.

Load or Reset defaults

  1. CMOS restore defaultsEnter CMOS setup.
  2. In CMOS setup look for an option to reset the CMOS values to the default setting or an option to load the fail-safe defaults. With many CMOS setup screens there will be a function key to do this; for example, the F5, F6, F9, F11, or F12 key like shown in the picture. Other setups may list an option that you can arrow over to using the arrow keys and press Enter.
  3. When found and selected you'll likely be asked if you're sure you want to load the defaults press Y for yes or arrow to the yes option.
  4. Once the default values have been set make sure to Save and Exit and not just exit.

Reset Configuration Data

In addition to restoring the system defaults if you've recently added new hardware or resetting the default values did not help resolve your boot issues you may also want to reset the configuration data. Note: Not all CMOS setup screens have this feature.

Under advanced

If you're working on a computer with a Phoenix BIOS that has Main - Advanced - Security - .... across the top of the screen you can get to this setting by using the right arrow to move over to Advanced and under Advanced arrow down to Reset Configuration Data and changing the value from Disabled or No to Enabled or Yes.

Once the above has been done press the F10 key and save and exit CMOS setup.

In PnP/PCI Configurations

If you're working with a Phoenix BIOS that has different options and one of them is PnP/PCI Configuration move the cursor down to this option and press Enter. Within the PnP/PCI Configurations change the Reset Configuration Data from Disabled to Enabled.

Once the above has been done press the F10 key and save and exit CMOS setup.

Hard reset the CMOS

Caution: When inside your computer make sure you're aware of ESD and all it's potential dangers.

CMOS batteryIf the above steps do not reset the CMOS settings we suggest removing the CMOS battery for 5 minutes causing the computer to forget all settings. Removing the CMOS battery like the one shown in the picture causes the system to lose all CMOS settings including the password. To do this locate and remove the CMOS battery on the motherboard for at least five-minutes. After this has been done put the battery back into the computer and turn it back on.

If your computer does not have a CMOS battery or you're unable to find it you'll need to do a hard reset on the CMOS using a jumper or dip switch on the motherboard. Information on finding these can be found through your computer or motherboard documentation.

Additional information

  • See the BIOS and CMOS definitions for further information and related links.