HP Desktop PCs - CMOS Battery: Generic Troubleshooting and Reasons

[A_Gayathri]

If your HP desktop PC shows clock errors, CMOS errors, or similar startup messages, the CMOS battery on the system board likely needs replacement. HP recommends first checking your specific computer model for exact instructions, and if unavailable, using the generic steps below.

Common reason

A failing cmosbattery can cause:

• Clock/date errors at startup
• CMOS-related error messages
• Loss of BIOS settings
  
  

Recommended first step

Find your computer model number and check the HP Support page for a Maintenance and Service Guide or Hardware Reference Guide with model-specific CMOS/RTC battery instructions.

Generic troubleshooting and replacement steps

1. Turn off the computer and disconnect the AC adapter from the desktop.
2. Press the power button 10 times to fully discharge electricity from the system.
3. Open the computer to access the system board.
4. Remove or disconnect the CMOS battery from the system board.
5. Confirm all power sources are removed, including the CMOS battery.
6. Press the power button for at least 60 seconds to drain remaining power and reset CMOS values.
7. Reinstall the CMOS battery and reassemble the computer.
8. Reconnect the AC adapter.
9. Press and hold the power button for 20 seconds.
10. Release the power button and let the system boot.
11. If needed, confirm BIOS time is set to 00:00. If not, repeat the procedure and hold the power button for 120 seconds in step 6.
    
    

Detailed cautions

• Metal edges can cut skin inside the PC.
• ESD protection is important: work on a non-carpeted floor, use a static-dissipative surface if possible, and wear a grounded ESD wrist strap.
  
  

Best practice

HP recommends using the model-specific guide whenever available, because CMOS/RTC battery procedures can vary by system board.

Source : HP Desktop PCs - Removing and replacing the CMOS battery

What is a CMOS Battery? Complete Guide to Computer CMOS Battery Function & Replacement

HP Desktop PCs - Removing and replacing the CMOS battery

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