The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Clearing CMOS can get a PC past a startup failure when incorrect BIOS settings are the cause—but it will not fix a failed power supply or damaged hardware. First distinguish a PC that has no power from one that powers on but will not boot or display an image; those symptoms call for different checks.
What “dead PC” means—and when clearing CMOS may help
“Dead” is often used for three different problems. AMD’s boot-failure guidance separates a system with no power from one that fails to boot, and a system that powers on without displaying an image. Clearing CMOS is most relevant when the motherboard’s saved BIOS settings are preventing startup.
- No power: No fans move and no motherboard lights appear. Check the outlet, power cable, PSU switch, and internal power connections first. A CMOS reset is not a diagnosis for a system with no signs of power.
- No boot or POST: The system receives power but does not complete its startup checks or reach the operating system. A problematic BIOS setting is one possible cause; memory, CPU compatibility, or another hardware issue may also be responsible.
- No display: The system appears to power on, but the monitor shows no image. Check the monitor, input, cable, graphics hardware, and diagnostic indicators as well as considering BIOS settings.
Clearing CMOS restores the motherboard’s BIOS configuration to its defaults. It can remove a setting that is blocking startup, but it does not repair a faulty component or prove that the rest of the hardware is healthy.
Before resetting CMOS, protect your BIOS settings
A reset removes customized BIOS settings. Intel’s CMOS-reset instructions, reviewed April 23, 2025, advise recording settings before clearing CMOS; the system date and time may also need to be set again afterward.
#1 Best Overall
- Please check the 4th image.It clearly demonstrates the connector detail,2 pins and 2 wires with REVERSE polarity.
- The core component is CR2032,with thickness of 3.2mm and diameter of 20mm
- The core component was produced by Japanese battery giant,which assure the quality of RTC( real time clock) battery and a long life span
- The professional packaging solution,anti-static bag, provides the sufficient protection on the cmos batteries.
- The sticky pad on the other side of CMOS battery provides the flexible application when you replace the CMOS battery.Easily peel off the paper backing and replace it with convenience.
- Find the manual for the exact motherboard model, not just the computer brand or case.
- Record any custom BIOS settings you rely on. If you cannot access BIOS now, note that a reset will restore defaults and may require reconfiguration later.
- Shut down and disconnect power as directed by the manufacturer before using a jumper, button, or battery method.
- Do not guess a jumper position, button location, battery type, or waiting time. These details vary by motherboard.
How to clear CMOS safely
Use only a method documented for your motherboard. Board makers may provide a dedicated clear-CMOS button, a jumper, or a battery-removal procedure; the layout and sequence are model-specific. ASUS includes CMOS clearing in its broader no-power, no-boot, and no-display troubleshooting guide, alongside power, CPU, memory, graphics, monitor, and minimal-component checks.
Use the documented button or jumper
- Look up the exact motherboard model and open its manual or manufacturer support instructions.
- Shut the PC down and disconnect the power supply from AC power. Follow the board’s instructions for any additional power-off steps.
- Locate the designated clear-CMOS button or jumper identified in that manual. Use it only in the specified way and for the specified duration.
- Restore the system to its normal configuration, reconnect power, and try starting it.
Use the documented battery method
- Confirm that the motherboard manual describes battery removal as a CMOS-reset method and specifies how to access the battery.
- Shut down and disconnect AC power before opening the case or handling the battery.
- Remove the battery only as directed, wait for the duration specified for your board, then reinstall it in the correct orientation.
- Reconnect power and start the PC. If it reaches BIOS, restore any settings you recorded and correct the date and time if needed.
Waiting periods are not universal. For example, MSI’s no-power/no-display instructions, dated January 6, 2025, specify a five-minute wait for the battery-reset method, while its separate BIOS-access troubleshooting article, dated June 14, 2023, describes waiting 3–5 minutes before reinstalling the battery. Follow the procedure for your own board rather than treating either interval as a universal rule.
Rank #2
- We use high quality battery,manufactured by Japanese battery giant to produce the CMOS battery.
- The battery comes with a standard connector,MOLEX 51021-0200 1.25mm Pitch connector.Please check the polarity of connector on 4th images and the compatibility on the description page
- Connector:2 pins and 2 wires;Red(+,Posive),Black(-,Negative)
- The professional anti-static packaging bag provides the safe protection on the battery product. Please refer to the last image
- Each item is tested before shipping.what you see is what you get.
If the PC still will not start, follow the symptom
A failed CMOS reset does not establish what part is faulty. Continue with safe, staged checks recommended by the motherboard or processor manufacturer; do not probe energized components.
Recommended Free Tools
If there are no signs of power
- Confirm the outlet works, the power cable is seated, and the power-supply switch is on.
- Check that the motherboard’s power connectors are firmly seated, following the board and PSU manuals.
- If the system remains completely unpowered, seek qualified support rather than treating CMOS clearing as a fix.
If the PC powers on but fails POST or shows no image
- Check CPU support and BIOS compatibility for the exact motherboard and processor combination.
- Reseat or test memory and graphics hardware as directed by the manuals. If there are multiple modules, consult the board manual for the recommended configuration.
- Verify the monitor is powered on, set to the correct input, and connected to the appropriate graphics output.
- Disconnect external devices and nonessential hardware, then try a minimal configuration if the manufacturer’s instructions support it.
- Read motherboard debug LEDs or beep indicators if available; use the manual to interpret them rather than guessing from a light or sound.
ASUS’s troubleshooting sequence covers power, CPU, memory, graphics, monitor, minimal-component testing, CMOS clearing, Q-LEDs, and buzzer checks. MSI’s no-display guidance also describes a minimal POST configuration and debug LEDs. If those checks do not isolate the fault, contact the motherboard or system manufacturer, or a qualified repair technician.
Rank #3
- Voltage: 3V; Capacity: Diameter: 20.5mm, Height: 6.5mm. Connector: CR2032-MX51021.
- These batteries cannot be charged, it is very dangerous to charge them. Please keep out of reach of children. Do NOT SWALLOW.
- Suitable for Computer Replacement Battery
- No leak, excellent cost performance and long cycle life. Keep the cells in 40%-60% charged state during long period storage. We recommend to charge the battery every 3 months after receipt of the battery and maintain the voltage, and store the battery in a cool and dry place. Please keep out of reach of children.
- Suitable for M11x R1 R2 Area-51 13 15 17 18 R2 R3 R4 M14x R1 R2 M17x M18x R2 Area-51 M9700 M9750 E6520, E6420, E6320, XFR E6420, ATG E6420, E5530, E6230, E5430, E6530, E6430
What a successful CMOS reset does—and does not—tell you
If the PC starts after a reset, a BIOS setting may have contributed to the failure. The reset alone does not identify which setting caused it, confirm that every component is healthy, or guarantee that the problem will not return. Restore only settings you understand, one at a time, so a problematic configuration is not immediately reintroduced.
The “dozen” in the headline is the author’s account, not a success rate established by manufacturer guidance. The practical takeaway is narrower: CMOS clearing is a low-complexity, model-specific troubleshooting step for some startup problems, not a universal cure for a PC that appears dead.
Quick Recap
Rank #4
- Rome Tech BIOS DELL CMOS battery best suits to replace your broken or non-working old battery - we provide premium quality only
- COMPATIBLE with Dell Latitude 6430u / Dell Latitude 7300 / Dell Latitude 7430 / Dell Latitude 7490 / Dell Latitude E5470 / Dell Latitude E7240 Ultrabook
- Enjoy extended reliability of the CR2032 battery and heat shrink of a high caliber - the CMOS Battery DELL Latitude will last you for a long time
- The size of the entire unit is extremely small - will fit in almost any electronic device requires 3V Battery connector with 2 pins and 2 wires
- Quick and simple CMOS battery for DELL Latitude installation takes only 10 minutes of your time. Try our customer service for resolving any issues during battery replacement
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
