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Decoding BIOS beeps

Decoding BIOS beeps 5 October 2023

BIOS is the first program that runs after the computer or server is started. The BIOS is recorded on the motherboard chip and stored separately from the main hardware files. The BIOS performs the following important functions:

  • Provides I/O operation.
  • Manages component settings.
  • Manages the further launch of all device systems.
  • Conducts Power-On Self Test (POST) – any error that may be present in an element of a computing device will be detected at the initial stage.

There are only a few options for informing the user about the cause of the malfunction (the reason is the limited resources of the chip with BIOS). The most reliable notification option is sound notification. This method consists in determining the error in a particular element by tracking the number of signals and their duration. Next, we will consider the most popular types of sound encoding, since they differ between various motherboard providers.


Type of sound signal Description
1 short

No POST errors detected

2 short

RAM parity error

3 short

Problems in the first 64KB RAM

4 short

The system timer is not working correctly

5 short

CPU error

6 short

Incorrect operation of the input device controller

7 short

System board error

8 short

Incorrect operation of video memory

9 short

Incorrect BIOS checksum

10 short

CMOS memory write error

11 short

Cache memory error

1 long, 2 short

Problems with the video adapter

1 long, 3 short

2 long, 2 short

Incorrect operation of the drive controller

No signals

Error in power supply or system board


Type of sound signal



Power supply failure


Power supply or motherboard error

1 short

No POST errors detected

2 short

Error when starting the video system

1 short and blank screen

The video adapter is not working correctly

1 short, 1 long

Motherboard error

2 short, 1 long

Mono/CGA malfunction

3 short, 1 long

EGA/VGA malfunction


Type of sound signal


1 short

No POST errors detected

1 long, 2 short

Video adapter error (you need to check if it is connected)

1 long, 3 short

Video adapter error or keyboard malfunction (depends on BIOS version)

1 long, 9 short

BIOS chip error (impossible to read the BIOS)

1 long or repetitive

RAM failure

2 short

Not a serious error (you can easily fix it in the BIOS settings)

3 long

Malfunction of the keyboard controller

No signals

Error in system board or power supply


Type of sound signal


1 short

No POST errors detected

2 short

Global system startup error

1 long, 1 short

CMOS BIOS memory checksum error

1 long, 2 short

Video adapter malfunction

1 short, 2 long

RAM operation error

7 repetitive signals

AGP fault


Malfunction of RAM

Troubleshooting during system boot

If you receive a sound notification about an error, you can try to restore the system boot. First, it is recommended to check the connection of the device element that caused the system to malfunction.

Another reason for the failure may be incorrect BIOS settings. This error can be resolved by performing a factory reset. The BIOS control panel menu should contain the Load Default Settings function. Factory reset can be performed using this function.

By disconnecting the BIOS battery for 15 minutes, you can reset the parameters. It is useful, if the device still does not turn on, and it is not possible to perform a software setup.

Usually minor faults can be eliminated by rebooting the system. Anyway, there are various methods of solving the problem under consideration:

  • connecting a missing element,
  • replacing a controller,
  • formatting data, etc.