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Published 10th February 2001 by

Decode the sequence of beeps to determine a BIOS or system error.

The computer POST (Power On Self Test) checks the internal hardware for errors and connection before starting the boot process. If the computer passes the POST, the computer may give a single beep as it starts the bootloader. However, if the computer fails the POST, the computer will either not beep or generate a beep code that tells the user the source of the problem. You can use the table below to identify the cause of the error according to the code from the beeps.

There are a large number of manufacturers, each with differing codes, but here are the most common codes, with AMI BIOS being the most popular.

AMI BIOS Beep Codes

1 Short BeepSystem OK
2 Short BeepsParity error in the first 64 KB of memory
3 Short BeepsMemory failure in the first 64 KB
4 Short BeepsMemory failure in the first 64 KB Operational of memory or Timer 1 on the motherboard is not functioning
5 Short BeepsThe CPU on the motherboard generated an error
6 Short BeepsThe keyboard controller may be bad. The BIOS cannot switch to protected mode
7 Short BeepsThe CPU generated an exception interrupt
8 Short BeepsThe system video adapter is either missing, or its memory is faulty
9 Short BeepsThe ROM checksum value does not match the value encoded in the BIOS
10 Short BeepsThe shutdown register for CMOS RAM failed
11 Short BeepsThe external cache is faulty
1 Long, 3 Short BeepsMemory Problems
1 Long, 8 Short BeepsVideo Card Problems
Two tone sirenCPU fan or temperature alert


1 long, 2 shortIndicates a video error has occurred and the BIOS cannot initialize the video screen to display any additional information.
1 long, 3 shortVideo card not detected (reseat video card) or bad video card
Beeps repeating endlesslyRAM problem
Repeated high frequency beeps while PC is runningOverheating processor
Repeated beeps alternating high & low frequencyIssue with the processor (CPU), possibly damaged

Standard Original IBM POST Error Codes

1 short beepSystem is OK
2 short beepsPOST Error - error code shown on screen
No beepPower supply or system board problem
Continuous beepPower supply, system board, or keyboard problem
Repeating short beepsPower supply or system board problem
1 long, 1 short beepSystem board problem
1 long, 2 short beepsDisplay adapter problem (MDA, CGA)
1 long, 3 short beepsDisplay adapter problem (EGA)
3 long beeps3270 keyboard card

IBM POST Diagnostic Code Descriptions

100 - 199System Board
200 - 299Memory
300 - 399Keyboard
400 - 499Monochrome Display
500 - 599Colour/Graphics Display
600 - 699Floppy-disk drive and/or Adapter
700 - 799Math Coprocessor
900 - 999Parallel Printer Port
1000 - 1099Alternate Printer Adapter
1100 - 1299Asynchronous Communication Device, Adapter, or Port
1300 - 1399Game Port
1400 - 1499Colour/Graphics Printer
1500 - 1599Synchronous Communication Device, Adapter, or Port
1700 - 1799Hard Drive and/or Adapter
1800 - 1899Expansion Unit (XT)
2000 - 2199Bisynchronous Communication Adapter
2400 - 2599EGA system-board Video (MCA)
3000 - 3199LAN Adapter
4800 - 4999Internal Modem
7000 - 7099Phoenix BIOS Chips
7300 - 73993.5" Disk Drive
8900 - 8999MIDI Adapter
11200 - 11299SCSI Adapter
21000 - 21099SCSI Fixed Disk and Controller
21500 - 21599SCSI CD-ROM System

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