You press the power button. The fans spin up with a hopeful whir, but the screen stays black. Maybe you were messing around with overclocking settings in the BIOS, or perhaps your RAM just decided to be difficult today. It’s frustrating. You’re staring at a dead hunk of metal and plastic that worked perfectly fine twenty minutes ago. Before you start panic-searching for a local repair shop or assume your motherboard is fried, you need to learn how to CMOS reset your system. It’s basically the "hard reboot" for your hardware's memory, and nine times out of ten, it’s exactly what saves a bricked PC.
The CMOS (Complementary Metal-Oxide-Semiconductor) is a tiny bit of physical memory on your motherboard. It stores BIOS settings like the system clock, boot order, and those aggressive voltage tweaks you thought were a good idea at 2 AM. When these settings get corrupted or become incompatible with your hardware, the system gets confused. It gets stuck. By resetting the CMOS, you’re wiping that volatile memory and forcing the motherboard to load its factory default settings.
It’s like giving your computer a brief moment of amnesia so it can remember how to be a computer again.
The classic "Pop the Battery" method
Honestly, this is the way most people do it. It feels a bit primitive, but it works. Every standard motherboard has a CR2032 lithium coin-cell battery—the same kind you’d find in a car key fob or a kitchen scale. This battery provides a tiny trickle of power to the CMOS chip even when the PC is unplugged, which is why your computer knows what time it is even after being in a box for three months.
First, shut everything down. Unplug the power cable from the back of the PSU. This is non-negotiable. If you leave it plugged in, there’s still "standby power" flowing through the board, and you might not get a clean reset. Once it's unplugged, press and hold the PC’s power button for about 15 seconds. This drains any remaining electricity stored in the capacitors.
Now, open the side panel. You’re looking for that silver coin battery. Sometimes it’s hidden under a massive triple-fan GPU, so you might have to pull the graphics card out first. Once you see it, there’s usually a little metal clip holding it in place. Push the clip, and the battery should pop up.
Leave it out. Go get a glass of water. Wait at least five minutes. While some people say 30 seconds is enough, I’ve seen stubborn boards hold onto data for a couple of minutes. To be safe, let it sit. Put the battery back in, plug it in, and try to boot. You’ll likely see a message saying "CMOS Checksum Error - Defaults Loaded." That’s a good sign. It means it worked.
Using the CMOS jumper (The "Pro" way)
What if the battery is tucked behind a thermal shroud or you just don't want to risk breaking a plastic clip? Most motherboards have a dedicated set of pins for this exact purpose. They are usually labeled something like CLEAR_CMOS, CLR_RTC, or JBAT1.
Check your manual. No, seriously, find the PDF online for your specific model (like an ASUS ROG Strix B550-F or an MSI Mag Z790). The manual will show you exactly where these two or three pins are located. Usually, they’re near the bottom right of the board.
If it's a two-pin header, you just need to bridge them. You can use a dedicated jumper cap if your motherboard came with one, but a flathead screwdriver works just as well. With the power off and unplugged, touch the tip of the screwdriver to both pins simultaneously for about 10 seconds. This completes the circuit and shorts the CMOS memory to ground, wiping it instantly.
For three-pin setups, the process is slightly different. There will be a plastic cap covering two of the pins (let's say pins 1 and 2). To learn how to CMOS reset in this configuration, you move the cap to pins 2 and 3 for a few seconds, then move it back to the original position. Never try to boot the computer while the jumper is in the "clear" position. You won't like the results.
High-end boards and the "Easy" button
If you spent $400 on a flagship motherboard, you probably don't need to hunt for pins or batteries. Look at the Rear I/O—the area where your USB ports are. Many modern enthusiast boards from EVGA, Gigabyte, and ASRock have a physical "Clear CMOS" button right there.
It is incredibly convenient.
You still need to shut down the PC, but you often don't even have to open the case. Just hold that button down for a few seconds. Some boards even have a button directly on the PCB inside the case, usually glowing red or white. It’s a lifesaver for overclockers who are constantly pushing their RAM timings too far and causing boot loops.
Why your PC might need this in 2026
We are seeing more "smart" BIOS features than ever before. Modern AI-overclocking and "Auto-undervolting" tools are great until they aren't. Sometimes these algorithms suggest a voltage that is just a hair too low for your specific silicon lottery, and the system refuses to post.
Another common culprit? XMP and EXPO profiles.
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You buy a 6000MHz RAM kit, enable the profile in the BIOS, and suddenly you're looking at a black screen. This happens because the memory controller on your CPU can't quite handle the speed, but the BIOS is now "locked" into trying that speed every time it starts. A CMOS reset is the only way to tell the board, "Hey, let's go back to the safe 4800MHz speed so I can actually get into the menu to fix this."
A few warnings and "Gotchas"
It isn't all sunshine and rainbows. When you figure out how to CMOS reset and actually execute it, you are losing everything in that firmware.
- RAID Configurations: If you have a RAID 0 or RAID 1 array set up through your motherboard's controller, a CMOS reset might flip the SATA mode back to AHCI. Your drive might appear "unformatted" or missing until you go back into the BIOS and re-enable RAID mode. Don't format the drive! Your data is still there; the motherboard just forgot how to read it.
- TPM and Encryption: If you use BitLocker or other hardware-based encryption that relies on the fTPM (Firmware Trusted Platform Module), resetting the CMOS can sometimes trigger a security recovery. Make sure you have your BitLocker recovery key saved in your Microsoft account or on a USB drive before you start poking around your BIOS settings.
- Fan Curves: If you spent hours making your PC whisper-quiet by setting custom fan curves, those are gone. Write down your percentages or take a photo of the graph with your phone before you reset, if you have the chance.
- Resizing BAR: For gamers, remember that "Re-size BAR" (which helps GPU performance) is usually OFF by default. You'll need to go back in and turn that on along with "Above 4G Decoding" once you get back into the system.
Troubleshooting when a reset doesn't work
So you pulled the battery, you held the power button, you waited ten minutes, and... nothing. Still a black screen.
At this point, the issue likely isn't a bad setting in the CMOS. It’s time to look at the "POST Code" LEDs on your motherboard. Most modern boards have four tiny lights labeled CPU, DRAM, VGA, and BOOT. If the "DRAM" light is lit up red, a CMOS reset might not be enough; you might have a dead stick of RAM or a piece of dust in the slot.
Try a "single stick boot." Take out all your RAM except for one stick in the second slot. Reset the CMOS again. If it boots, you know one of your other sticks is the problem. Hardware troubleshooting is a game of elimination. The CMOS reset is just the first, easiest step in that game.
Actionable Steps for a Successful Reset
To ensure you don't actually damage your components while trying to fix them, follow this specific order of operations:
- Safety First: Turn off the PSU switch and pull the plug. Touch a metal part of the case to discharge static from your body.
- The Drain: Hold the PC power button for 15 seconds. This is the step most people skip, and it's why their resets fail.
- Choose Your Method: Use the battery pull for older boards or the jumper method for newer ones without buttons.
- The Waiting Game: Give it 5 minutes. Use this time to blow some compressed air into your dusty filters.
- The Re-Entry: Reinstall the battery or move the jumper back. Plug in and boot.
- The Re-Config: Immediately enter the BIOS (usually by tapping Del or F2). Re-enable your XMP/EXPO profiles, set your boot drive priority, and fix the system clock.
If you're using a laptop, the process is way more annoying. Most modern laptops don't have a CMOS battery anymore; they use a portion of the main internal battery to maintain settings. For these, you often have to hold the power button for a full 30 to 60 seconds while the device is off to trigger a hardware-level reset. Check your specific manufacturer's support page for "RTC Reset" instructions, as brands like Dell and Lenovo have very specific button-press sequences for this.
Resetting the CMOS is a fundamental skill. It’s the "turn it off and back on again" of the hardware world. Once you’ve done it a couple of times, that "black screen of death" becomes a lot less scary and a lot more like a minor inconvenience.