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Computer beeps (IBM BIOS, AWARD BIOS, AMI BIOS, Phoenix BIOS)

Each time the computer is turned on, the diagnostic self-test program starts automatically when the POST (Power-On-Self-Test) power is turned on, which is “recorded” in the BIOS ROM.

POST checks all important components of the computer: monitors the health of the processor, CMOS, supporting motherboard chips, and also conducts a quick test of RAM. Information about how the computer diagnostics went is given to the computer speaker in the form of a special sound signal.

If the computer is working normally, that is, the POST diagnostic program has successfully completed, you will hear one short beep, and then the computer’s operating system will start loading.

When an inoperable computer component is detected, the POST diagnostic program generates a special sound signal (a sequence of short and long beeps) characterizing the detected error, and the computer stops its operation.

If the computer issued a sequence of short and long beeps and stopped working, you need to count the number of beeps for their subsequent analysis. You can turn off the computer, wait about 30 seconds and turn it on again. After counting the beeps, find your combination of beeps in the table corresponding to your computer's BIOS. In the tables that are shown on this page, you will find a decoding of the sound signals. Thus, even without special diagnostic tools, it is possible to localize the malfunction of the personal computer.

Since the contents of the IBM BIOS ROM were copyrighted (that is, it could not be copied to other firms), most other computer manufacturers were forced to use independent BIOS ROMs. The BIOS of these independent companies were almost completely compatible with the IBM BIOS, but the sound code of the diagnostic POST program for each independent BIOS manufacturer was different, and did not match the sound code of the IBM BIOS sound signals.

Table 1. IBM BIOS Beeps Value

Type of sound signal Beep value
One short Normal POST completion, all OK
Missing Faulty power supply
Continuous Faulty power supply
Repeat short Faulty power supply
One long and one short Faulty motherboard
Single beep and blank screen Defective video system
One long and two short Faulty video system (Mono / CGA)
One long and three short Faulty video system (EGA / VGA)
Two short Faulty video system (no monitor connected)
Three long Faulty motherboard (keyboard controller error)

Table 2. The significance of the sound signals AWARD BIOS

Type of sound signal Beep value
One short Normal POST completion, all OK
Missing Faulty power supply
Single beep and blank screen Defective video system
One long and two short Defective video system
One long and three short No monitor connected
Two short Any minor error
Three long Faulty motherboard (keyboard controller error)

Table 3. AMI BIOS Beeps Value

Type of sound signal Beep value
One short Normal POST completion, all OK
Two short RAM Test Error
Three short RAM Test Error
Four short Faulty motherboard (system timer error)
Five short Processor is faulty
Six short Faulty motherboard (keyboard controller error)
Seven short Faulty motherboard (virtual mode error)
Eight short Faulty video adapter or video memory test error
Nine short BIOS Checksum Error
Ten short CMOS read / write error
Eleven short Faulty motherboard (cache test error)
One long and three short Faulty motherboard (extended memory error)
One long and eight short Error during monitor test

Table 4. Value of Phoenix BIOS Beeps

Type of sound signal Beep value
1 - 1 - 3 CMOS read / write error
1 - 1 - 4 BIOS Checksum Error
1 - 2 - 1 Faulty motherboard (system timer error)
1 - 2 - x Faulty motherboard
1 - 3 - x Faulty motherboard
1 - 4 - 1 Faulty motherboard
1 - 4 - 2 RAM Test Error
1 - 4 - 3 Faulty motherboard (system timer error)
1 - 4 - 4 Error while accessing the port
2 - x - x RAM test error (any combination starting with two beeps)
3 - 1 - x RAM Test Error
3 - 1 - 4 Faulty motherboard
3 - 2 - 4 Keyboard controller faulty
3 - 3 - 4 Faulty video adapter or video memory test error
3 - 4 - x Faulty video system
4 - 2 - x Faulty motherboard
4 - 3 - x Faulty motherboard
4 - 3 - 4 Faulty motherboard (real time clock error)
4 - 4 - 1 Serial Port Test Error
4 - 4 - 2 Parallel Port Test Error
4 - 4 - 3 Mathematical coprocessor test error


Note: x is any number from 1 to 4, if such a combination of numbers is not explicitly available.

Do not take this information as absolutely reliable. The audio coding may change as newer BIOS versions become available. In addition, it is necessary to take into account that sound signals facilitate the preliminary localization of a faulty component, indicating the right direction for further diagnostics of a computer malfunction.