The fans spin, the keyboard stays dark, and the monitor never wakes. You just pushed a memory profile, swapped a stick of RAM, or saved a BIOS change that the board refused to finish. A normal restart does nothing. That is usually when people look up how to reset CMOS on a motherboard, hoping a short hardware step will bring the machine back.
A CMOS reset does one narrow job. It returns firmware configuration to defaults when bad BIOS or UEFI settings block a normal startup. It does not erase files on the operating-system drive, and it does not repair a failed part or a corrupted firmware image. The useful move is to pick the method that matches what the board can still do, and to know which settings you will have to put back.
If setup still opens, load the defaults there before you open the case. If the screen never comes up, the physical clear methods come next, and the manual's timing beats any generic countdown.
Choose the Right CMOS Reset Method
If setup still opens, load optimized defaults there. If it doesn't, try an onboard clear button, then the jumper, and leave battery removal for last.
Intel's processor support guide documents two principal hardware approaches: a dedicated CMOS-clear jumper, or removing the motherboard battery. Both return firmware settings to defaults. They don't repair failed hardware, a bad power supply, or a corrupted BIOS. Clearing CMOS wipes customized firmware values such as boot order, memory profiles, fan settings, and overclocking parameters. The milestone is firmware defaults, not data recovery.
A desktop that fails to POST after a failed overclock is usually a settings problem, and a jumper clear is the practical fix. A board stuck in a boot loop after a BIOS update may need that clear plus a separate firmware recovery step, because old settings and a damaged firmware image are different faults. Intel also notes that header location, pin layout, and wait time depend on the board, and some server boards use a much shorter interval than a typical desktop header. Unplug the AC cord before you touch exposed contacts.
| Method | Where you do it | Time needed | Tools | Main risk |
| Load Optimized Defaults in BIOS | Firmware setup screen | About 2 minutes | None | Setup must still open |
| Onboard Clear CMOS button | Rear I/O panel | Under 1 minute | None | Not every board has the button |
| CMOS clear jumper | Header near the battery | 1-5 minutes plus setup | Screwdriver or jumper cap | Cap left on the wrong pins |
| Battery removal | Coin cell holder | 1-15 minutes depending on the board | Hands only | Battery reinstalled with the wrong orientation |
The table sets the order. Start with the method that needs the least hardware, and only move down the list when that method isn't available.
How to Clear CMOS With the Jumper
A jumper reset is a direct fix when firmware settings prevent a normal boot. Before moving the cap, check the motherboard manual for the header location, pin layout, and reset interval. The seven steps below cover a typical desktop header, but the manual for your board takes priority.
- Shut down the computer, switch off the power supply, and unplug the AC cord.
- Press the case power button once to discharge remaining power.
- Find the clear-CMOS header in the manual. Common labels include CLRTC, CLR_CMOS, and JBAT1.
- For a three-pin header, move the jumper from pins 1–2 to pins 2–3, unless the manual specifies another arrangement.
- Leave it in place for the interval specified by the board's manual. Some desktop procedures call for minutes; others use only seconds.
- Return the jumper to its original position before reconnecting power.
- Plug in the AC cord, start the computer, enter setup, load defaults, and save.
Why the wait depends on the board
Do not apply one wait time to every motherboard. The Intel desktop board guidance calls for 1–5 minutes, while Intel's server service guide specifies 5–10 seconds for its three-pin header procedure. Those instructions cover different boards, so follow the documentation for your exact model rather than treating either interval as universal.
| Board type | Jumper action | Wait before restoring | Source |
| Typical Intel desktop board | Follow the board's Clear CMOS header procedure | 1–5 minutes | Intel desktop board guidance |
| Intel server board | Move pins 1–2 to 2–3, then restore | 5–10 seconds | Intel server service guide |
| MSI boards with JBAT1 | Place jumper cap across JBAT1, then remove | 5–10 seconds | MSI manual |
| ASUS two-pin CLRTC header | Short the two pins with a cap or metal object | 5–10 seconds | ASUS FAQ |
MSI's H510M-PLUS II manual gives a short JBAT1 procedure: turn off and unplug the system, place a jumper cap across JBAT1 for about 5–10 seconds, then remove it before starting the computer. ASUS's clear-CMOS FAQ describes a similar method for a two-pin CLRTC header, shorting the pins with a cap or metal object for about 5–10 seconds while the system is off and unplugged.
Practical rule: Remove the cap from the clear pins before powering on. Leaving it there prevents you from completing the procedure correctly.
If the header labels are difficult to see, use the manual's board diagram to confirm the pins before moving the jumper.
How to Reset CMOS by Removing the Battery
Pull the coin cell for 1–5 minutes, or for 10–15 minutes when the desktop-board procedure asks for the longer wait. Battery removal is the last method because it is slower and easier to get wrong on a crowded board.
- Shut down, unplug the AC cord, and disconnect peripherals.
- Open the chassis and touch bare metal on the case so you discharge static.
- Find the coin cell, usually a CR2032, and note which face is positive before it comes out.
- Release the retaining clip gently with a fingernail or a plastic tool. Don't pry against nearby capacitors.
- Wait for the interval printed in your manual, not a guess from another brand.
- Reinsert the cell with the positive face as you noted, and press until the clip locks.
- Reconnect power and boot into setup.
Why a battery pull clears settings
The original IBM PC, introduced in 1981, stored configuration on motherboard DIP switches. The IBM PC AT that followed used a Motorola MC146818 real-time-clock chip with battery-backed memory. That chip provided 64 bytes, part of it for system settings. Later IBM-compatible PCs kept BIOS configuration in battery-backed CMOS RAM, which is why pulling the cell, or electrically clearing that memory, resets stored configuration and leaves the operating system and personal files alone. The BIOS reference history is the backdrop for every modern procedure. Intel's current advice is to record positive and negative orientation, then wait 1–5 minutes. Another Intel desktop-board procedure leaves the cell out for 10–15 minutes. Timing still isn't universal.
A dead cell often shows up as the wrong date and time after power loss, or as settings that won't stick between shutdowns. A fresh battery fixes that retention problem. It does not, by itself, repair a corrupted BIOS image.
Using the Onboard Button or BIOS Defaults
The fastest route doesn't involve the case at all. If the PC reaches the firmware screen, enter setup, open the Exit or Save page, and choose Load Optimized Defaults or Load Setup Defaults. Save and exit, often with F10. Many boards also bind that load action to F5 or F9. The on-screen key bar is the reliable guide, because the label moves between vendors.
When the rear button is enough
An onboard Clear CMOS button, usually on the rear I/O of higher-end ATX boards, needs no tools and takes well under a minute.
- Power the PC off and unplug it.
- Find the button on the rear panel. It is often recessed so a cable can't press it by accident.
- Press it with the power supply switched on only if your manual says that is required. Many boards want the system fully unplugged.
- Power up and read the first boot screen for a settings-reset message.
A clear started from inside setup can leave a few values in place, while a full hardware clear drops custom profiles, boot order, and fan curves back to factory behavior. If the machine feels slower after defaults, XMP or EXPO is probably off. That is expected, not a new fault.
If the board has no rear button and setup never opens, this route is closed. Move to the jumper.
Record Your Settings and Take Safety Steps First
Before clearing CMOS, check whether you can still open BIOS setup. If you can, loading BIOS defaults is the simplest route. A physical clear is useful when setup will not open or the board's manual calls for it, but neither option repairs failed hardware, a corrupted operating system, or a faulty firmware image. Resetting CMOS restores settings; it does not reflash firmware.
Write down settings you may need to restore. Photograph each relevant BIOS page, especially storage mode, memory profile, boot order, fan curves, virtualization, and custom security options. A reset can remove overclocks and undervolts, disable XMP or EXPO, and change other settings. The PC may then run memory at default speeds or fail to boot Windows if its storage mode no longer matches the installed configuration.
- Storage mode: Record whether the system uses AHCI, RAID, or VMD. Changing it after Windows is installed can prevent the disk from booting.
- Memory profile: Note the selected XMP or EXPO profile and its speed.
- Security and encryption: Keep your BitLocker recovery key available if device encryption is enabled. A firmware change can trigger a recovery prompt.
- Boot and fans: Photograph the boot order, fan curves, virtualization setting, and custom security options.
Take basic precautions before touching the board. Disconnect AC power, press the case power button once to discharge remaining power, and touch the chassis before handling components. Keep your fingers clear of the CMOS header contacts.
A clear can also make sense after replacing RAM or a processor, since saved settings may not suit the new configuration. For example, a replaced memory kit may start at default speeds until its profile is enabled again. Follow your motherboard manual for the reset method and timing, which can differ by board. Intel's troubleshooting guidance is a general troubleshooting resource, not evidence for every CMOS-specific effect, so use the board manual for those instructions.
Confirm the Reset and Decide Your Next Step
A successful clear usually announces itself. Many boards show a message that BIOS settings were reset and ask you to enter setup. ASUS's official instructions tell you to press F1 when prompted, open the UEFI BIOS Utility, and reconfigure. That message is the proof. A reset doesn't only flip a hidden hardware flag. It restores firmware defaults, so boot order, memory profiles, fan controls, and other custom options have to be set again before normal use.
What to check on the first boot
Confirm four things before you restore anything fancy.
- Clock: Date and time are sensible, which also hints the coin cell still holds a charge.
- Hardware inventory: The CPU and the full RAM capacity show up at the right size.
- Boot device: The operating-system drive is listed, even if it isn't first yet.
- Stability: The system completes a few restarts without dropping back into a no-POST state.
Restore settings in groups, not all at once. Enable the memory profile and reboot. Put boot order back and reboot. Set the storage mode only if Windows is already prepared for it. Fan curves come last, because they don't decide whether the disk is found.
Switching from RAID or VMD to AHCI after Windows is installed can stop the system from booting even though the drive is healthy. If you photographed the old mode, put that mode back before you chase cables.
When defaults aren't enough
If the board posts and runs, restore settings from your photos and keep those photos. If it still fails to POST after a clean reset, the reset was not the fix. There is no reliable industry-wide success rate for this procedure, so treat it as a settings test, not a guaranteed repair.
Work the hardware in a fixed order. Reseat the RAM in the slots the manual requires, then test one stick at a time. Check that the graphics card is seated and that both motherboard and GPU power leads are fully home. Listen for a failing power supply that spins fans and then drops out. If the board offers a BIOS recovery feature, use that only after a clean defaults boot has already failed, because recovery is for a bad firmware image, not for an overclock the chipset rejected.
A reset restores defaults, and defaults are the baseline for diagnosis.
NeoTeo publishes practical hardware guides, troubleshooting walk-throughs, and plain-language explainers for PC builders who would rather follow a board manual than guess at a jumper. If a clear-CMOS job is only the start of a bigger repair, or you want more hands-on coverage of firmware, parts, and retro builds, visit NeoTeo.
