The BIOS is the “Basic Input/Output System” of a computer. It is a piece of firmware that is saved on a tiny chip in the mainboard of almost every computer. The basic function of the BIOS is to enable com­mu­ni­ca­tion between the operating system and the hardware com­po­nents. Every time the system is started up, the BIOS runs a sort of self-test. This test is called the “POST”, which stands for “Power-On Self-Test”

If an error occurs during the POST, the BIOS emits a specific signal (a beep code) via the system loud­speak­ers to alert the user of a specific problem. How you open the BIOS depends on your computer – different man­u­fac­tur­ers use different methods. The BIOS update procedure also varies depending on the man­u­fac­tur­er. Read on to find out what the most common computer beep codes mean.

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BIOS beep codes for Award/Phoenix

1x short No errors detected during the self-test
2x short Non-specified error; more details displayed on screen
Con­tin­u­ous beep Memory or graphics card not detected
Repeated short beeps In­suf­fi­cient power supplied to the moth­er­board
1x long RAM error
1x long, 1x short Moth­er­board error
1x long, 2x short Graphics card error
1x long, 3x short Keyboard con­troller failure; graphics card error (in later BIOS versions)
3x long Com­mu­ni­ca­tion error between keyboard and moth­er­board

BIOS beep codes for AMI

1x short Incorrect in­ter­ac­tion between RAM and moth­er­board
1x long No errors detected during the self-test
Con­tin­u­ous beep Power supply error
1x long, 1x short Fault on moth­er­board
1x long, 2x short Graphics card not detected
1x long, 3x short Video memory error
2x short Parity error in the first 64 kB of memory
2x long, 2x short Video memory error
3x short, 3x long, 3x short Defective RAM; RAM must be replaced
5x short Problem with processor
6x short Cannot enter BIOS in safe mode
7x short Processor or graphics card error
8x short Display memory error in graphics card
9x short CMOS battery error
10x short Error in shutdown register of CMOS RAM
11x short Error in external cache memory

BIOS beep codes for IBM

1x short No errors detected during the self-test
2x short Error during the POST; more details displayed on screen
No beep Power supply/system board/processor error; often related to power supply
Con­tin­u­ous beep Power supply/system board/keyboard problem
Repeated short beeps Power supply or system board problem
1x long, 1x short System board problem
1x long, 2x short Graphics card problem (Mono/CGA video error)
1x long, 3x short Graphics card problem (EGA video error)
3x long Keyboard problem

BIOS beep codes for DELL

Dell beep codes are all the same length. You need to listen for how often a beep is repeated after a short pause. This is indicated by the figures and dashes in the following table. For example, “1 – 2” means “Beep – Beep Beep”. The beep codes in the table below are used by Dell-OptiPlex systems. Other Dell systems such as Inspiron or Vostro in­cor­po­rate flashing LEDs to com­mu­ni­cate error messages.

1 – 1 – 2 Mi­cro­proces­sor register failure
3 – 2 – 4 Keyboard con­troller test failure
3 – 3 – 1 NVRAM power loss
3 – 3 – 4 Video memory test failure
3 – 4 – 1 Screen ini­tial­iza­tion failure
4 – 2 – 2 Shutdown failure
4 – 4 – 4 Cache test failure

BIOS beep codes for Macintosh

One beep, repeating every 5 seconds No RAM installed
3x short, 5-second pause, 3x short RAM did not pass data integrity check
1x long while you hold down the power button An EFI ROM update is in progress (only ap­plic­a­ble to computers man­u­fac­tured before 2012)
3x long, 2x short, 3x long EFI ROM error or Mac is in EFI ROM recovery mode

BIOS beep codes for MR

MR systems use low and high beeps. These are shown in the table as “L” and “H” re­spec­tive­ly.

LH-LLL BIOS failure (re­place­ment may be required)
LH-HLL DMA page register failure (possible board fault)
LH-LHL Keyboard con­troller self-test failure
LH-HHL RAM seated in­cor­rect­ly (e.g. after re­place­ment)
LH-LLH Mainboard failure
LH-LLLL Memory bank 0 pattern test failure
LH-LHLLH CMOS RAM read/write test failure
LH-HHLLH Real-time clock failure
LH-LLHLH BIOS/RAM failure with graphics card, error in video card address line
LH-HLHLH Keyboard con­troller failure
LH-LHHLH RAM parity error
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