A red light on your motherboard means internal hardware is either plugged-in incorrectly or not working.

• Internal hardware examples include the CPU, RAM, or a graphics card.
• Sometimes a dead CMOS battery may be the culprit.
• Boot errors on the hard drive where the primary OS is installed may also cause a red light.

The red light always appears after the computer turns on, but generally, it will not boot, enter the bios, or display content on the monitor.

The specific error depends on the motherboard and where the red light is. Some motherboard manufacturers include labels on the board to explain what's wrong. Older motherboards may have a single, unlabeled red LED, making it more difficult to discern what's going on.

If you cannot tell what's wrong at a glance (something's not plugged in correctly, etc.), you can always refer to the user manual included with your motherboard.

How to Read a Red Light on a Motherboard

Newer boards have four main indicators, and the red light will be next to each label. Those are:

BOOT: A red light near the BOOT indicator means something is wrong with the boot devices, which would be the hard drive. More specifically, it's the hard drive where the OS is stored.

VGA: A red light near the VGA or GPU indicator means the graphics card is not detected or seated correctly.

DRAM: A red light near the DRAM indicator means that a RAM module is not seated correctly. If you can see that side clamps on either side of a RAM stick are not locked down, that's probably the issue.

CPU: A red light near this indicator means the motherboard does not recognize the CPU, which could mean many things. The CPU might not be plugged in correctly, or one of the pins is bent. It could also be the CPU fan is not plugged in. Finally, a dead CMOS battery can also cause the red light to trigger.

Important:

Most motherboards have a single red LED to indicate a hardware malfunction, but they don't include any information about what's wrong. Some older motherboards have a speaker to help with system errors. If your motherboard has a speaker, make sure it's attached as the motherboard can, if equipped, play tones to indicate what the problem is. You'd need to consult the manual included with your motherboard to learn which tone corresponds to which problem.

What the Red Light in CPU Means

Each motherboard LED tells you where the problem is, but not necessarily what it is.

The red light near the CPU label indicates that something is wrong with the processor, and it's one of the more common reasons you will encounter the red light.

Here are some reasons why the CPU indicator would trigger:

• It may not be seated properly, which can mean it's not plugged in correctly or the pins are bent. 
• It may also mean the motherboard's power cable is not plugged in correctly.
• The CPU fan cable is not plugged into the header all the way.
• The CMOS battery is dead.
• The CPU you have installed is defective.

How to Troubleshoot Red Light Errors on a Motherboard

These steps apply to all motherboard models, including older boards without labeled LED indicators.

Always ensure the computer's power is off and the power supply switch is set to 0 before disconnecting or connecting any internal hardware.

1. Disconnect the affected hardware and reseat it to ensure it's plugged in correctly.If you have an older board, you can skip this step.

2. Reset the bios of your motherboard. Most of the time, it's a jumper that you can short (by plugging in a jumper). You will need the user manual for your board if you don't know the steps to do this. You might also check the official support website of your motherboard's manufacturer. Alternatively, you can remove the CMOS battery and leave it out for at least five minutes.

3. Replace the CMOS battery. A dead battery will trigger a red LED indicator, which can leave you pulling out your hair. You may even consider trying this first before anything else.

4. If all else fails, disconnect and unplug all hardware starting with the GPU, any hard drives, the RAM, and the CPU. Inspect the connectors and pins for damage or debris. Grime and dust may build up on an old motherboard which can cause problems. You can remove it by carefully cleaning the connectors with a soft pencil eraser. You should also remove all external peripherals, including the mouse, keyboard, external drivers, printers, and ethernet cable.

5. One by one, connect the devices to your computer and try booting it up. Critical hardware includes the CPU and RAM. If you have multiple RAM modules, you can leave one plugged in and the rest disconnected. If the computer appears to boot and there is no red light present, even when there is no video, then it's likely you've found the problem. Try booting without the GPU (graphics card) and a single stick of RAM.

6. If you've checked all parts and the problem persists, the problem may be either a defective motherboard or a dying or defective power supply. In some cases, when the power supply fails, it still supplies power to the motherboard and components, and everything, including the system fans, will turn on, yet the computer will not boot.

How Can You Tell if Your Motherboard Is Dying?

The best way to tell if your motherboard is dying, or failing, is to follow the troubleshooting steps discussed here. Unplug all minor hardware from the board and try to boot with minimal connections.

If the computer still doesn't turn on or POST, the board or the power supply is likely the culprit. More often than not, the power supply is the problem. However, if you replace the power supply and the computer still doesn't boot, you know it's the motherboard.

In rare cases, you may be able to detect damage on the board, including burnt or defective headers, transistors, and other components. A board that has been killed by a static shock will not show any signs of damage, however.

• What does a red flashing light mean on an AMD motherboard?

  A red blinking light could appear because of a video card issue, built-up debris, or a CPU recognition error. If labeled, see which indicator is lighting up, and run through the steps above. Consult the user manual or customer support if the documentation doesn't include what the blinking or solid light patterns mean.

• Why is there a red LED light on the motherboard after I installed RAM?

  This light could mean that your RAM is faulty or not correctly seated. Check that it's secure and ensure you're putting it in the correct slot or according to the manufacturer-recommended configurations. Also, double-check that you've purchased compatible RAM for your machine.

• Why Does My Motherboard Have an Orange Light?

  An orange light, usually solid, means power is supplied to the motherboard, which is normal. Some motherboards may display a persistent orange light, while others will not. The power button may flash different orange colors with select computers to indicate a problem. A solid orange light means there's a problem with the motherboard, while a blinking orange light means there's something wrong with the power supply.