cmos battery


How To Clear CMOS Motherboard battery

Clearing the CMOS on your motherboard will reset your BIOS settings to their factory defaults. After clearing the CMOS, you’ll need to access the BIOS setup utility and reconfigure your hardware settings. You might need to clear the CMOS for several reasons but usually you’ll want to clear the CMOS to help troubleshoot or solve certain PC problems like hardware compatibility issues. Here are 3 different ways to clear the CMOS. Any one method is as good as any other but you may find one of them easier or whatever problem you might be having may restrict you to clearing the CMOS in a particular way.


Clear the CMOS with the “Factory Defaults” BIOS Option Menu

The easiest way to clear the CMOS is to enter the BIOS setup utility and choose to “Reset BIOS Settings” to their factory default levels. The exact menu option in your motherboard’s BIOS may differ but look for phrases like reset to default, factory default, clear BIOS, load setup defaults, etc. This option is usually located at near the bottom/end of your BIOS options.

Note: The directions I’ve linked to here are how to access your BIOS utility but do not specifically demonstrate how to clear the CMOS in your BIOS utility. It should be easy enough, however, as long as you can find that “reset” option.

How To Access the BIOS Setup Utility

You may need to access the BIOS setup utility for a number of reasons like managing memory settings, configuring a new hard drive, changing the boot order, resetting the BIOS password, etc. Entering BIOS is actually very easy once you determine which key or combination of keys on your keyboard to press to access BIOS. Follow the easy steps below to access the BIOS setup utility on your computer.

Difficulty: Easy

Time Required: Accessing the BIOS setup utility for your computer usually takes less than 5 minutes

Heres How:

1. Turn on your PC or restart it if it’s already on.

2. Watch for a “entering setup” message in the first few seconds after turning on your computer. This message varies greatly from computer to computer and also includes the key or keys you need to press to enter BIOS.

Here are some common ways you might see this BIOS access message:

o Press [key] to enter setup

o Setup: [key]

o Enter BIOS by pressing [key]

o Press [key] to enter BIOS setup

o Press [key] to access BIOS

o Press [key] to access system configuration

3. Quickly press the key or keys instructed by the previous message to get into BIOS.

Note: You may need to press the BIOS access key several times to enter BIOS. Don’t hold the key down or press it too many times or your system may error or lock up. If that happens, just restart and try again.

BIOS Setup Utility Access Keys for Popular

Computer Systems

Acer Aspire, Power, Veriton, Extensa, Ferrari, TravelMate, Altos

· Press Del or F2 immediately after powering on.

· The BIOS on the Acer Altos 600 server uses the Ctrl+Alt+Esc key and the F1 key for advanced options.

· Older Acer computers may use also use the F1 or Ctrl+Alt+Esc keys to access BIOS.

Compaq Presario, Prolinea, Deskpro, Systempro, Portable

· Press F10 while the cursor in the top right corner of the screen is blinking.

· Older Compaq computers may use the F1, F2, F10, or Del key to give access to BIOS.

Dell XPS, Dimension, Inspiron, Latitude. OptiPlex, Precision, Vostro

· Press F2 when the Dell logo appears. Press every few seconds until the message Entering Setup appears.

· Older Dell desktops and laptops may instead use Ctrl+Alt+Enter or Del to enter BIOS.

· Older Dell laptops may use Fn+Esc or Fn+F1.

eMachines eMonster, eTower, eOne, S-Series, T-Series

· Press Tab or Del while the eMachine logo displays on screen.

· Other eMachine computers may use F2 to enter BIOS.

Fujitsu LifeBook, Esprimo, Amilo, Tablet, DeskPower

· Press F2 once the Fujitsu logo appears.

Gateway DX, FX, One, GM, GT, GX, Profile, Astro

· Press the F1 key repeatedly after restarting the computer.

· Some older Gateway computers use F2 to access the BIOS Setup utility.

Hewlett-Packard (HP) Pavilion, TouchSmart, Vectra, OmniBook, Tablet

· Press the F1 or F10 key after restarting the computer.

· HP Tablet PCs may use F10 or F12.

· Other HP computers may allow access to BIOS using the F2 or Esc keys.


· Press F1 immediately after powering on the computer.

· Older IBM computers (including some laptops) may utilize the F2 key for BIOS entry.

Lenovo (formerly IBM) ThinkPad, IdeaPad, 3000 Series, ThinkCentre, ThinkStation

· Press F1 or F2 after powering on the computer.

· Older Lenovo products allow access to BIOS using Ctrl+Alt+F3, Ctrl+Alt+Ins, or


Micron (MPC Computers) ClientPro, TransPort

· Press F1, F2 or Del immediately after powering on the PC.

NEC PowerMate, Versa, W-Series

· Press F2 to enter the BIOS Setup.

Packard Bell 8900 Series, 9000 Series, Pulsar, Platinum, EasyNote, imedia, iextreme

· Press F1, F2, or Del to enter BIOS.

Sharp Notebook Laptops, Actius UltraLite

· Press F2 after the computer starts.

· Some very old Sharp PCs require a Setup Diagnostics Disk to access BIOS.

Shuttle Glamor G-Series, D’vo, Prima P2-Series, Workstation, X Mini XPC, Surveillance

· Press F2 or Del on startup.

Sony VAIO, PCG-Series, VGN-Series

· Press F1, F2 or F3 after turning on the computer.

Toshiba Portégé, Satellite, Tecra, Equium

· Press F1 or Esc after powering on to access BIOS.

· Press F12 on a Toshiba Equium.

· ARI / ALR / AST (Advantage) – Press the Ctrl+Alt+Esc or Ctrl+Alt+Del keys.

· Cybermax – Press the Esc key.

· Tandon – Press the Ctrl+Shift+Esc keys.

BIOS Setup Utility Access Keys for

Popular Motherboards

BIOS Access Keys for ASUS, MSI, GIGABYTE, EVGA, Intel, and More!

abit ab9, an7, an8, av8, aw9d, be6, bh6, ic7, in9, ip35, kn8, kn9, etc.

· Press Del while the PRESS DEL TO ENTER SETUP message is displayed to access the BIOS setup utility.

ASRock 4coredual, 775dual, 939dual, k7s41gx, p4v88, k7vm3, etc.

· Press F2 right after the computer starts up.

ASUS p5b, a7v600, a7v8x, a8n, a8v, k8v, m2n, p5k, p5n, etc.

· Press Del right after starting the computer to enter BIOS. A few ASUS motherboards use

Ins instead.

BFG 680i, 8800gtx, 6800gt, 7600gt, 7800gs, 7950gt, etc.

· Press Del when the …enter setup message briefly displays at the bottom of the screen after powering on the computer.

BIOSTAR 6100, 550, 7050, 965pt, k8m800, p4m80, ta690g, tf7050, etc.

· Press the Del key while the full screen logo is showing on screen, immediately after starting the computer.

DFI LANParty Ultra, Expert, Infinity 975x, NF3, NF4, cfx3200, p965, rs482, etc.

· Press the Del key when the Press DEL to enter setup message appears, immediately after the memory test.

ECS Elitegroup k7s5a, k7vta3, 741gx, 755-a2, 945p, c51gm, gf7100pvt, p4m800, etc.

· Press either the Del or F1 key to enter the BIOS Setup Utility.

EVGA 790i, 780i, 750i, 680i, 650i, e-7150/630i, e-7100/630i, 590, etc.

· Enter BIOS by pressing Del immediately after powering on the computer.

Foxconn c51xem2aa, 6150bk8mc, 6150bk8ma, c51gu01, etc.

· Press Del to enter the BIOS Setup Utility.

GIGABYTE ds3, p35, 965p, dq6, ds3r, k8ns, etc.

· Press Del during POST, right after the computer is turned on.

Intel d101ggc, d815eea, d845, d850gb, d865glc, d875pbz, d945gccr, d946gtp, d975xbx, etc.

· Press F2 during the initial boot process to enter the BIOS setup utility.

JetWay jm26gt3, ha04, j7f3e, hi03, ji31gm3, jp901dmp, 775gt1-loge, etc.

· Enter BIOS setup by powering on the computer and pressing Del immediately.

Mach Speed Viper, Matrix, pm800, 917gbag, v6dp, s755max, etc.

· Press Del after the boot process begins to enter the BIOS configuration utility.

MSI (Micro-Star) k8n, k9n, p965, 865pe, 975x, k7n2, k9a2, k8t neo, p7n, p35, x48, x38, etc.

· Press Del while the Press DEL to enter SETUP message displays on screen after powering on the computer.

PCChips m810lr, m811, m848a, p23g, p29g, p33g, etc.

· Press Del or F1 to enter the BIOS utility.

SAPPHIRE PURE CrossFire 3200, a9rd580Adv, a9rs480, CrossFireX 770 & 790FX, PURE Element 690V, etc.

· Press Del after powering on to get into BIOS.

Shuttle “bare bones” and motherboards including ak31, ak32, an35n, sn25p, ai61, sd37p2, sd39p2, etc.

· Press Del or Ctrl+Alt+Esc at the Press DEL to enter SETUP message that appears right after turning on the computer.

Super Micro c2sbx, c2sbm, pdsba, pdsm4, pdsmi, p8sc8, p4sbe, etc.

· Press the Del key at any time during the boot process.

TYAN Tomcat, Trinity, Thunder, Tiger, Tempest, Tahoe, Tachyon, Transport and Bigby motherboards including K8WE, S1854, S2895, MP S2460, MPX S2466, K8W S2885, S2895, S2507, etc.

· After starting the system, press the Del or F4 key to start the BIOS setup utility.

XFX nForce 500 Series, 600 Series, 700 Series, etc.

· Press Del during the boot process, immediately after the computer is turned on.

BIOS Setup Utility Access Keys for Major

BIOS Manufacturers

BIOS Access Keys for Phoenix, Award, AMI, and More!

AMI (American Megatrends) AMIBIOS, AMI BIOS

· Press Del when after powering on the computer.

· Some older motherboards that use AMIBIOS may prompt for the F1 or F2 key instead.

Award Software (now part of Phoenix Technologies) AwardBIOS, Award BIOS

· Press the Del key to enter the BIOS Setup Utility on nearly all AwardBIOS powered motherboards.

· Some older systems using Award’s BIOS software asked for Ctrl+Alt+Esc to enter


DTK (Datatech Enterprises) DTK BIOS

· Press the Esc key to enter BIOS, right after powering on the PC.

Microid Research MR BIOS

· Press F1 to access the BIOS setup utility.

Phoenix Technologies Phoenix BIOS, Phoenix-Award BIOS

· Press Del during the Power On Self Test, immediately after the computer starts.

· Many older Phoenix BIOS systems required Ctrl+Alt+Esc, Ctrl+Alt+Ins, or

Ctrl+Alt+S to access BIOS.

If you’re still having troubles entering BIOS or can’t figure out what company supplied the BIOS on your motherboard, here are some keyboard commands you might want to randomly try in addition to the any of the ones listed above:

· F3

· F4

· F10

· F12

· Tab

· Ctrl+Alt+F3

· Ctrl+Alt+Del

· Ctrl+Alt+Shift+Del (using Del from the keypad)

· Ctrl+Insert

· Ctrl+Shift+Esc

· Fn+[any “F” function key] (on some laptops)

BIOS Access Keys for Gateway, Lenovo, Toshiba, Dell, Acer, and More!


1. See a picture instead of a message? Your computer may be configured to show your computer’s logo instead of important BIOS messages. Press Esc or Tab while the logo is showing to remove it.

2. See the message but didn’t catch which key to press? Some computers start too quickly to see the BIOS access message. If this happens, press the Pause/Break key on your keyboard to freeze the screen during startup. Press any key to “unpause” your computer and continue booting.

3. Having troubles pausing the startup screen? If you’re having problems pressing that pause button in time, turn on your computer with your keyboard unplugged. You should receive a keyboard error which will pause the startup process long enough for you to see the keys necessary to enter BIOS!

4. Tried everything and still can’t get in? Some PCs with both PS/2 and USB connections are configured to only allow USB input after the POST. This means that if you’re using a USB keyboard, it could be impossible to access BIOS. In that case, you’d need to connect an older PS/2 keyboard to your PC to access BIOS.

5. Accessing the BIOS is independent of any operating system on your computer because the BIOS is part of your motherboard hardware. It doesn’t matter if your PC is running Windows 7, Windows Vista, Windows XP, Linux, Unix, or no operating system at all – any instructions for entering the BIOS setup utility will be the same.

Clear the CMOS Using the Motherboard Jumper


Another way to clear the CMOS is to short the “CLEAR CMOS” jumper on your motherboard, assuming you have one (most motherboards do). Open your computer and look around your motherboard for a jumper labeled like this. These jumpers are usually located near the BIOS chip itself or near the CMOS battery.

Using the Motherboard “Clear CMOS” Jumper

Using the Motherboard “Clear CMOS” Jumper or Dipswitch settings Many motherboards feature a set of jumpers or dipswitches that will clear the CMOS and wipe all of the custom settings including BIOS passwords. The locations of these jumpers / dipswitches will vary depending on the motherboard manufacturer and ideally you should always refer to the motherboard or computer manufacturers documentation. If the documentation is unavailable, the jumpers/dipswitches can sometimes be found along the edge of the motherboard, next to the CMOS battery, or near the processor. Some manufacturers may label the jumper / dipswitch CLEAR – CLEAR CMOS – CLR – CLRPWD – PASSWD – PASSWORD – PWD. On laptop computers, the dipswitches are usually found under the keyboard or within a compartment at the bottom of the laptop. Please remember to unplug your PC and use a grounding strip before reaching into your PC and touching the motherboard. Once you locate and rest the jumper switches, turn the computer on and check if the password has been cleared. If it has, turn the computer off and return the jumpers or dipswitches to its original position.

Clear the CMOS by Reseating the CMOS Battery



Yet another way to clear the CMOS is to reseat the CMOS battery. By removing and then reinstalling the CMOS battery, you remove the source of power that saves your computer’s BIOS settings. If you can’t access BIOS and also can’t locate the clear CMOS jumper, clearing the CMOS this way should do the trick.

How to replace the CMOS battery


How to replace the CMOS battery.


Like any battery the computer CMOS battery can fail or lose its charge.


If your computer is losing its time or date settings, or you are receiving a message CMOS Read Error, CMOS checksum error, or CMOS Battery Failure, first try leaving the computer on for 24-hours. In some cases this can charge the battery and resolve your issue. This often resolves CMOS battery related issues when a computer has been left off for several months. If this does not resolve your issue follow the below steps.

Locate your CMOS battery

When inside your computer make sure you’re aware of ESD and all it’s potential dangers.


Open the computer case and find the battery on the computer motherboard, verify that it will be accessible and that it can be removed. Most computers today use a coin cell CMOS battery as shown in the image to the right. If you are unable to locate your CMOS battery refer to your motherboard or computer documentation or contact your computer manufacturer for additional assistance in locating it.

Obtain battery information

Unfortunately, most manufacturers will not list the exact type and model of your CMOS battery; therefore, once you have located the battery, write down all information about the battery (Voltage, chemistry, wiring, and packaging). If possible, remove the battery and take it to the location you plan on purchasing a new battery from. The part number for this battery for most computers is CR2032. Additional buying information can be found on our battery buying tips page. Removing the battery

When inside your computer make sure you’re aware of ESD and all it’s potential dangers. If you’re computer is using a coin cell battery similar to the above example picture. Removing the battery is relatively simple. use your fingers to grab on the edge of the battery and pull it up and out of the container holding it. Some motherboards have a clip holding the battery down. If your computer has this clip you may need to use one had to move the clip up and the other hand to pull the battery out. Unfortunately, not all CMOS batteries are removable; some manufactures will only allow a replacement battery to be added. If you’re not using a coin cell battery and are not able to determine how to remove it refer to your motherboard or computer documentation or contact your computer manufacturer for additional assistance in removing the battery or how to insert a new replacement battery. Users with computers that do not have removable batteries only options to install a new battery will most likely also need to set a jumper when adding the new battery into their computer.

Insert the new battery

Once you have purchased a new battery, remove the old battery (as instructed above) and replace it with the new battery.

Enter CMOS values

Once the battery is replaced turn on the computer and resetting the CMOS values to the defaults. After the values have all been entered make sure to save the settings before exiting. Many

CMOS setups allow you to press a key (such as F10) to save values and exit all in one action. If after following all the above steps you continue to experience the same error when your computer starts or your computer is still unable to keep the stored values it’s likely that you’re experiencing a more serious issues. Most likely causes are bad power supply or bad motherboard.


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