Reset the CMOS on PC to Restore Default Settings in the BIOS

I have had several people asking me lately about problems with their PC not booting, or hanging up before loading into Windows.

In most of these cases based on what they are describing to me it sounded as though there could be a configuration issue with the BIOS on the computer.

It is not uncommon to make changes to the BIOS on your system. In many cases these changes can improve or customize the performance of your PC. But in some cases the changes that are made can lead to problems with the system that keep the computer from booting properly.

In this case it is best to reset the BIOS on your system. This can be done in two different ways.

• By removing the CMOS battery.
• Using the 3 Pin CLRTC Jumper to Reset the BIOS Settings.

Let’s take a look at each one of these methods and how it is done.

(Make sure you have removed the AC Power Cable from your system when performing these steps. Any electrical charge that remains in the system can keep the CMOS & BIOS settings from being reset.)

Removing the CMOS Battery in Your PC to Reset the BIOS

The first thing you need to do is identify the CMOS battery. It is a shiny metallic circle on the motherboard about the size of a Nickel. It will normally be laying flat so you can see the circle shape but in some cases it is mounted on it’s side, so you may only be able to see it from an angle.

1. Once you have identified the CMOS battery you need to remove it from the motherboard.
2. The CMOS Battery is usually held in by either a clip or tab. In either case you should be able to take a small flathead screwdriver to move the clip or tab aside to free the battery from its mount.
3. (A ball point pen also works well if you do not have a small flathead screwdriver on hand.)
4. Now that you have removed the battery let the system sit for about 1 minute with the battery removed. This will allow any remaining electrical charge in the system to dissipate.
5. Once a minute has passed you can reinsert the battery back into the motherboard.

The CMOS should now be cleared and your BIOS settings reset. You can now try rebooting your motherboard and resetting BIOS options as needed.

Clearing BIOS Settings Using the CLRTC 3 Pin Jumper

I always recommend the battery method listed above to customers when resetting their BIOS settings. The reason being is that the battery method seems to do a more reliable job of clearing your BIOS settings.

To clear the BIOS via the CMOS 3 Pin jumper perform the following steps.

1. First reference your motherboard manual for help identifying the CLRTC 3 Pin jumper. It can actually have different names but the most common seems to be “CLRTC” which is why I am referencing that here.
2. If you do not have your motherboard manual check the motherboard for 3 Pin jumpers. Look for the labels that are silk-screened onto the motherboard and try to find one that says: CLRTC, JMOS
3. Once you have located this jumper, make a note of the position is in on the 3 Pins on the motherboard. You should see a series of 3 Pin with 2 of them being covered by the jumper.
4. Take the jumper and remove it from the two pins it is currently covering. Move the jumper over so that it covers the previously exposed pin of the 3. The jumper should now be covering the middle pin and the previously uncovered pin.
5. Leave the jumper in place for about 1 minute. As with the battery method above make sure there is no AC power cable connected to your system as any small voltage can allow the system to retain the BIOS settings.
6. Once a minute has passed remove the jumper from the pins you just placed it on, and move it back to its original position on the motherboard.

Once you have done this you should now be able to boot your motherboard up and check to see if your BIOS settings have been reset. If your computer does not POST after you used the Jumper to clear the BIOS double check to make sure you have the jumper back in its proper original position.

Clear the BIOS / CMOS Settings on Your Motherboard Summary

You should now know how to properly clear the BIOS settings from your motherboard. This is handy to know incase you ever have any problems booting your computer as it is a good generic fix for many possible issues.

In a NO POST situation, this is usually one of the first things I will try as it can clear up issues about 50%+ of the time.

If you are still having problems with the system or are running into a persistent NO POST situation check out my NO POST Troubleshooting guide for more information on how to resolve the issue.

Troubleshooting a Motherboard that Won’t Turn On – Faulty Motherboard

There are three main questions that you need to ask yourself that will determine the route you take when troubleshooting a NO POST motherboard combo.

• Is this a “NEW” Motherboard Combo I just assembled? (With new parts)
• Is this an older Motherboard Combo I just assembled with “USED” parts?
• Is this a Motherboard Combo in a system that just suddenly stopped working?

If you answered “Yes” to questions #2 or #3, you are possibly looking at a piece of bad (or incompatible) hardware that is preventing your motherboard combo from POSTing. If that is the case you will need to diagnose the individual parts to ensure they are working. Read the guides below to check for faulty PC parts.

- How to Check for a Bad CPU and Motherboard. (Coming Soon)

- How to Check for Bad Memory.

- How to Check for a Bad Power Supply.

If the Motherboard Combo you are working with is a new combo that you just put together with new parts, it may be a hardware configuration issue that is keeping the board from POSTing. In that case there are some common issues to look for to troubleshoot the problem.

(The troubleshooting steps below are effective if you have ensured that all of your hardware is in “working” condition. If you have not yet determined this refer to the links above.)

Troubleshooting Power to the Motherboard Combo

1. If your power supply has an ON/OFF (the black switch with a one and zero on it) make sure it is set to “ON” (set to the number one).
2. As you plugged into a power strip and if so, is the power strip set to on?
3. Is the outlet you are plugged into controlled by a wall switch? If so, make sure the wall switch is flipped to “ON”.
4. Do you have both the 20/24 pin ATX Power connection and the 4 pin ATX Power connection plugged into the board?
5. Reseat your ATX Power connections on the motherboard to ensure they are plugged in all the way. Do the same with the AC cable the plug that goes into your power supply.
6. To rule out your front panel wiring disconnect the wires from the motherboard and connect the two power pins with a flathead screw driver to start the computer.

Check for Configuration Issues with the PC Hardware

1. Clear the CMOS of the motherboard by using the Clear CMOS Jumper (Refer to your manual to identify this jumper) or by removing the CMOS battery from the motherboard. Make sure you do not have the AC power connected to the system when you clear the CMOS to ensure the system does not hold a small charge and retain it’s settings.
2. Remove any additional expansion cards from the system. (Sound cards, graphics cards, network cards, etc.)
3. Reseat the memory in the system. Make sure the memory is seated all the way in the socket and that the tabs on the socket are locked in and holding the memory in place.
4. Disconnect any drives (SATA or IDE) from the system, so that the only things hooked up the motherboard are the CPU, Memory, and Power Supply (And Video Card if needed).
5. Reseat your CPU and make sure it has been installed properly in the CPU Socket. Make sure the CPU is aligned correctly in the socket. Check the socket and CPU for any bent pins, lint, or other issues that may be keeping the CPU from making proper contact with the motherboard.

Perform an Isolated POST Test

Remove the motherboard from the case to make sure you are not running into any grounding issues that are keeping the system from POSTing. Make sure to test the motherboard on an isolated surface. For more information on how-to perform a Motherboard POST Test checkout the guide below.

Motherboard POST Test Tutorial

If none of troubleshooting steps listed above have resolved your issue you may be running into a problem with the hardware itself. If this is the case I would recommend contacting the manufacturer of the hardware for extended troubleshooting and RMA contact information to send the part in for replacement.

You can also contact the vendor that you purchased the hardware from if they provide technical support services or warranty coverage on the computer hardware they sell.

Motherboard POST Information – Troubleshooting and Diagnostic

To perform a POST TEST (Power On Self Test) on a motherboard you need four pieces of hardware.

• The Motherboard
• A CPU (Processor)
• Memory (RAM)
• A Power Supply

Depending on whether your motherboard has onboard video or not you may also need a Video Card for the POST Test.

01. A Good Motherboard Testing Area

Place your Motherboard on a non-conductive surface. A foam pad works great. Otherwise use the antistatic bag, or box the motherboard came in for a testing surface. (Make sure no metal is touching the motherboard or it may short out.)

02. Install the System Memory (RAM)

Install your memory onto your motherboard. Check the notch in the bottom of your memory to make sure it is oriented the correct way when you install it into your motherboard.

When you insert the RAM into the memory slots on the motherboard you should feel two tabs on each end of the memory socket snap into place. Check to make sure your RAM is seated level in the memory socket.

If it is not seated properly you will need to remove the memory and reinstall it. In the picture above you can see the tab has not locked the memory in place and the memory is not seated correctly. The tab should remain flush with the others once the memory has been installed properly.

03. Mounting Your CPU (Processor)

Next you will need to install your processor. All CPU sockets have a lever that needs to be opened to install the CPU. Make sure this lever is open so you can get the processor into the CPU Socket.

Picture #1 shows an Intel CPU Socket with the lever closed.

Picture #2 shows an AMD CPU Socket with the lever closed.

Before placing your processor in the CPU Socket check for an alignment indicator on the CPU.

Picture #1 – On Intel Processors there are two (2) notches on the bottom of the CPU that will line up with 2 notches on the CPU Socket.

Picture #2 – On AMD Processors this will be a small arrow marked on one corner of the CPU that aligns with a mark on the CPU Socket.

Make sure to note these indicators and double check that your CPU is aligned the correct way when you place it into the CPU Socket. This will help you avoid bent pins that may damage the CPU.

Once the Processor is installed securely in the CPU Socket you will need to close the socket and secure the lever on the CPU Socket. This will lock the CPU in place.

Once you have closed the lever on the CPU Socket you will need to install your CPU Heat Sync.

Picture #1 – Shows an Intel Processor mounted in the CPU Socket. The lever is closed locking the CPU in place.

Picture #2 – Shows an AMD Processor mounted in the CPU Socket. The lever is closed locking the CPU in place.

04. Installing the CPU Heat Sync (Cooler)

All retail box CPUs come with a CPU Heat Sync. You should have received one in the box when you purchased your CPU.

(Make sure to remove the plastic cooler on the bottom of the heat sync if it has one. DO NOT remove the grey square or circle on the bottom of the heat sync. This is known as the “heat patch” and is needed for the cooler to function properly.

AMD CPU Heat Sync

To install an AMD cooler you will need to mount the heat sync over the CPU. There are two tabs on each side of the heat sync that will lock onto notches on the CPU Socket. Make sure you align these when you place the heat sync on the CPU.

Once you have placed the heat sync on the CPU latch one of the tabs over the first notch. Once this has been done latch the other tab over the other notch. Once both latches are attached to the notches flip the lever on the heat sync over to increase tension and lock the heat sync in place.

(If you are having trouble getting the tabs to lock over the notches check the lever on the CPU and make sure it is not flipped in the direction that increases tension. If it is it will keep you from being able to get the tabs locked into place.)

Once the lever has been flipped and the cooler is locked into place the heat sync has been installed correctly.

Intel CPU Heat Sync

To install an Intel cooler you will need to place the heat sync on top of the CPU. Check where the wire from the heat sync plugs into your motherboard and make sure you have enough slack to reach. If you do not then rotate the cooler until the wire will reach.

Once you have the cooler placed on the CPU check for the four (4) holes in the motherboard near the CPU Socket. These holes are for the pegs on the cooler. Once you have the pegs aligned with these holes use your thumb to press down on each peg until you here a small click. This click indicates the peg is locked into place through the board.

If you do not hear the click look at the backside of your motherboard to ensure the peg locked into place. If it did not lock into place then try pushing the peg once again.

Once all four pegs have clicked into place the Intel cooler has been installed properly.

In the picture above you can see in the “Right” installation the ends of the peg have been spread apart by the black middle piece locking it in place. In the “Wrong” picture the peg has poked through the motherboard but has not been locked into place and will pop out.

05. Hookup the Power Supply to the Motherboard

Most Power Supply (PSU) units require two connections to the motherboard to provide power for a POST Test.

The first connection is the 20/24 pin ATX power connection. This will go into the 20/24 pin white connection on your motherboard. This is usually located near your memory sockets.

This connection is “keyed” meaning it will only fit one way. Align the notch on the 20/24 power cable with the tab on the 20/24 pin power socket. When you insert the connection you should feel a small click as the tab latches in place.

Now you need to plug in the 4 pin ATX power connection. This is usually located between your CPU and your IO ports.

This connection is also “keyed” so it will only fit into the socket one way. Once again align the notch on the cable with the tab on the socket and you should have trouble getting it to snap into place.

06. Installing a Video Card (Or not)

If you have an all in one motherboard you are ready to perform the motherboard POST test. Simply hookup your VGA (Monitor) connection and your PS2 Keyboard and Mouse connections.

If you do not have a spot to connect your monitor (VGA) cable then you probably need to install a video card.

Installation of the video card is very straight forward. You simply need to insert your video card into your PCI express socket (or AGP depending on how old the motherboard us.) You should feel the card snap into place.

Some cards do not feel like they lock in when they are inserted into the motherboard. If this is the case check the socket where the video card plugs into the motherboard and make sure it looks level.

Some video card slots have a tab, or notch on the side closet to your memory that is designed to lock the card into place. Check this tab and make sure it is latching properly if you are having trouble getting your video card installed.

07. Hooking Up Your Keyboard, Mouse and Monitor

Once you have everything in place you need to attach the cables for your mouse, keyboard and monitor. If you are using a video card make sure you attach your monitor cable to the correct VGA port.

Make sure to also connect the AC Cable to your power supply. Once the AC cable is connected check for a black switch on your power supply unit (PSU). This switch has a setting of one (1) or zero (0). One is “On” and Zero is “Off” so make sure this black switch is set to One “On”.

08. POST Testing Your Motherboard

To POST Test the motherboard we now need to turn the hardware on. To do this we will use a flat head screw driver to connect the power switch pins on the motherboard.

Refer to your motherboard manual for help in identifying these pins. These are commonly labeled red, black, or green but can vary depending on the motherboard. It is always best to refer to the manual to locate these pins.

Once you have located the two (2) pins for the power switch take your flathead screw driver and connect the two pins to power on the board.

When you tap them with the screw driver you should see your CPU fan start to spin. In a couple seconds you should hear a beep from your motherboard. One beep means the board has successfully POSTed.

(NOTE: Some motherboards do not have a speaker and may not beep.)

The main thing to look for is POST information on your monitor. Once you have POST Tested the motherboard you should see information displayed on your screen. If you see this information it is a sign that the computer has successfully completed the POST.

09. Completed POST Test

If you saw the information displayed on your screen you have successfully completed POST testing your board. You now know that all your basic hardware is functioning correctly and can proceed building your computer.

If your hardware did not complete the POST Test correctly you will need to look into troubleshooting your hardware.

I will be following up with articles on troubleshooting a NO POST motherboard combo and other common issues people run into.

Please feel free to ask any questions regarding the POST Test procedure and I will try to address them.