When starting a computer you see a message indicating a cmos error what is the most likely solution

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The information stored in the BIOS (System Setup), known as Extended System Configuration Data (ESCD), can occasionally become corrupt due to various reasons. These reasons include power events, incorrect settings, hardware incompatibility due to a specific setting, or a turn on self-test (POST) or video issues. In these cases, it is sometimes necessary to reset the BIOS or CMOS (Complementary metal–oxide–semiconductor) to factory default settings. In other circumstances, clear the nonvolatile random access memory (NVRAM) or perform a RTC Reset operation.

WARNING: The BIOS interface is designed for advanced users. Be sure about what changes you are making in the BIOS. Accidentally changing an unknown setting can prevent the computer from turning on, booting into the operating, or can cause potential loss of data.

NOTE: This process resets the BIOS to factory default settings, it does not clear the CMOS or NVRAM.

1. Turn on the computer.
2. Tap the F2 key several times until Entering Setup appears.
3. Reset the BIOS to factory defaults. The method to reset the BIOS varies between different computers:
   1. Click the Load defaults button.
   2. Or, press the F9 key to load default settings.
   3. Or, press the Alt+F key to load default settings.
4. Press the Esc key and select Save and exit or Exit.
5. Press the Enter key to save all changes and exit the BIOS setup screen.
6. The computer restarts.

WARNING: Clearing the CMOS or NVRAM using a jumper resets the passwords in the BIOS. This includes the BIOS user password, admin password, and hard drive password. This does not include any other passwords such as Windows login, online accounts, and so on.

   

NOTE: The RTCRST/PSWD jumper is not available on Dell laptops.

The Real-Time Clock Reset (RTCRST) jumper helps reset or clear the NVRAM on the computer. The ESCD information that is contained in the NVRAM can be cleared by following the steps that are mentioned below. The NVRAM is cleared when the jumper is set to the closed position and turning on the computer for 10 seconds.

NOTE: Dell desktop computers can be recovered from a turn on self-test or video failure by clearing the CMOS or NVRAM.

 

NOTE: The location of the RTCRST and PSWD jumper varies between different Dell desktops. For more information about jumper locations, see the User Manual of the Dell desktop.

1. Before you begin, follow the Safety Precautions When Working with Electronic and Electrical Equipment.
2. Turn off the computer and disconnect the power cable from the computer.
3. Remove the computer cover. For model-specific information, see the User Manual of the Dell desktop.
4. Locate the 2-pin password jumper labeled PSWD on the system board.
5. Remove the 2-pin jumper plug.
6. Locate the 2-pin CMOS jumper labeled RTCRST on the system board.
7. Move the 2-pin jumper plug from the password jumper to the pins on the CMOS jumper.
8. Plug the power cable to the computer and wait for 10 seconds for the CMOS to clear.
9. Disconnect the power cable from the computer.
10. Move the 2-pin jumper plug back to the password jumper.
11. Replace the computer cover. For model-specific information, see the User Manual of the Dell desktop.
12. Connect the power cable to the computer and turn on the computer.

Figure 1: Illustration of the jumpers on the system board of a Dell desktop computer.

How to clear the BIOS, CMOS, or NVRAM by reseating the CMOS battery

The BIOS can be reset to factory defaults my reseating the CMOS battery that is connected to the system board. This process is applicable for both Dell desktops and laptops. Follow the steps below if the PSWD or RTCRST jumpers are not accessible on a Dell desktop or if you are using a Dell laptop.

WARNING: Clearing the CMOS or NVRAM by reseating the CMOS battery resets the passwords in the BIOS. This includes the BIOS user password, admin password, and hard drive password. This does not include any other passwords such as Windows login, online accounts, and so on.

 

NOTE: The CMOS battery cannot be reseated on all Dell laptops. For model-specific information, see the User Manual of the Dell computer.

1. Before you begin, follow the Safety Precautions When Working with Electronic and Electrical Equipment.
2. Turn off the computer and disconnect the power cable from the computer.
3. If you are using a Dell laptop, disconnect the battery from the computer. For model-specific information, see the User Manual of the Dell computer. If your Dell laptop has a nonremovable battery, see the Dell knowledge base article How to Reset Real Time Clock (RTC) to Recover Your Dell Laptop.
4. Remove the computer cover. For model-specific information, see the User Manual of the Dell computer.
5. Locate the CMOS coin-cell battery (Figure 2 and 3).
6. Carefully, disconnect the coin-cell battery from the system board.
7. Press and hold the power button for 10-2- seconds to drain residual power.
8. Connect the coin-cell battery to the system board.
9. Close the computer cover.
10. Connect the battery and the power cable to the computer.
11. Turn on the computer.
12. A warning message appears indicating that the date and time is not set.
13. Press the F2 key to enter the BIOS screen.
14. Set the date and time according to your time zone.
15. Save and exit the BIOS screen.

Figure 2: Illustration of a coin-cell battery on the system board of a Dell desktop

Figure 3: Illustration of a coin-cell battery on the system board of a Dell laptop

How to clear the BIOS, CMOS, or NVRAM on Desktop computers without an RTCRST Jumper or serviceable Coin Cell battery

If your desktop computer was produced before April 2020, the computer most likely has a jumper based reset. Desktop computers manufactured after April 2020 use the RTC Reset ability.

Note: Desktop computers released after April 2020 should have RTC Reset enabled by default.

For desktop computers that use RTC Reset, hold the power button for 30 seconds. 

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Last Published Date

26 Sep 2022

Version

13

Article Type

Solution

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