Computer POST and beep codes

Updated: 07/13/2023 by Computer Hope
Computer internal speaker

The computer POST (power-on self-test) checks a computer's internal hardware for compatibility and connection before starting the remainder of the boot process. If the computer passes the POST, the computer may give a single beep (some computers may beep twice) as it starts and continues to boot. However, if the computer fails the POST, the computer may generate a beep code telling the user the source of the problem.

The most common causes of POST failures are problems with the following components.

If your computer has an irregular POST or a beep code not mentioned below, follow the POST troubleshooting steps to determine the failing hardware component.


Except for Dell and Mac, your computer or motherboard manufacturer is not the BIOS manufacturer. Determine the BIOS manufacturer for your computer's motherboard, then select the appropriate link below for beep code meanings.

AMI BIOS beep codes

Below are the AMI BIOS beep codes. However, because of the wide variety of different computer manufacturers with this BIOS, the beep codes for your computer may differ slightly from those listed below.

Beep Code Descriptions
1 short beep DRAM (dynamic random access memory) refresh failure.
2 short beep Parity circuit failure.
3 short beep Base 64 K RAM failure.
4 short beep System timer failure.
5 short beep Process failure.
6 short beep Keyboard controller Gate A20 error.
7 short beep Virtual mode exception error.
8 short beep Display memory Read/Write test failure.
9 short beep ROM BIOS checksum failure.
10 short beep How to replace the CMOS battery.
11 short beep Cache memory error.
1 long, 2 short beeps. Video card memory issue.
1 long, 3 short beeps. Conventional/Extended memory failure.
1 long, 8 short beeps. Display/Retrace test failed.
Two-tone siren Low CPU (central processing unit) fan speed, voltage level issue.

Award BIOS beep codes

Below are the Award BIOS beep codes. However, because of the wide variety of different computer manufacturers with this BIOS, the beep codes may vary.

Beep Code Description
1 long, 2 short beeps. Indicates a video error has occurred and the BIOS cannot initialize the video screen to display any additional information.
1 long, 3 short beeps. Video card not detected (reseat video card) or bad video card.
Beeps repeating endlessly. RAM problem.
Repeated high frequency beeps while PC is running. Overheating processor (CPU).
Repeated beeps alternating high & low frequency. Issue with the processor (CPU), possibly damaged.

If any other correctable hardware issues are found, the BIOS displays a message.

Dell beep codes

Beep Code Description
1 beep BIOS ROM corruption or failure.
2 beeps Memory (RAM) not detected.
3 beeps Motherboard failure.
4 beeps Memory (RAM) failure.
5 beeps CMOS battery failure.
6 beeps Video card failure.
7 beeps Bad processor (CPU).

For other Dell beep codes, please refer to Dell's beep codes and PSA diagnostics chart page.

IBM BIOS beep codes

Below are general IBM BIOS beep codes. However, because of the wide variety of models shipping with this BIOS, the beep codes may vary.

Beep Code Description
No beeps Why won't my computer turn on?
1 short beep Normal POST, computer is ok.
2 short beep POST error, review screen for error code.
Continuous beep No power, loose card, or short.
Repeating short beep No power, loose card, or short.
1 long, 1 short beep Motherboard issue.
1 long, 2 short beeps Video (Mono/CGA display circuitry) issue.
1 long, 3 short beeps. Video (EGA) display circuitry.
3 long beeps Keyboard or keyboard card error.
1 beep, blank or incorrect display. Video display circuitry.

Insyde beep codes

Beep Code Description
5 short and 1 long beep. Problem with the DMA page registers.
4 short, 1 long, 1 short beep. Circuit for refreshing RAM not working.
4 short and 2 short beeps. BIOS ROM checksum failure.
3 short, 1 long, 2 short beeps. CMOS RAM test failure.
3 short, 1 long, 1 short, 1 long beep. DMA controller failure.
3 short, 2 long, 1 short beep. Interrupt controller failure.
3 short and 3 long beeps. Keyboard self-test issue.
2 short, 1 long, 3 short beeps. Video card not found.
2 short, 1 long, 2 short, 1 long beep. No RAM installed or RAM not recognized.

Macintosh startup tones

Tones Error
Error tone. (two sets of different tones). Problem with logic board or SCSI (small computer system interface) bus.
Startup tone, drive spins, no video. Problem with video controller.
Powers on, no tone. Logic board problem.
High tone, four higher tones. Problem with SIMM (single inline memory module).

Phoenix BIOS beep codes

Below are the beep codes for Phoenix BIOS Q3.07 or 4.x.

Beep Code Description and what to check
1-1-1-1 Unconfirmed beep code. Reseat RAM chips or replace RAM chips as possible solution.
1-1-1-3 Verify real mode.
1-1-2-1 Get CPU type.
1-1-2-3 Initialize system hardware.
1-1-3-1 Initialize chipset registers with initial POST values.
1-1-3-2 Set in POST flag.
1-1-3-3 Initialize CPU registers.
1-1-4-1 Initialize cache to initial POST values.
1-1-4-3 Initialize I/O.
1-2-1-1 Initialize power management.
1-2-1-2 Load alternate registers with initial POST values.
1-2-1-3 Jump to UserPatch0.
1-2-2-1 Initialize keyboard controller.
1-2-2-3 BIOS ROM checksum.
1-2-3-1 8254 timer initialization.
1-2-3-3 8237 DMA (direct memory access) controller initialization.
1-2-4-1 Reset programmable interrupt controller.
1-3-1-1 Test DRAM refresh.
1-3-1-3 Test 8742 keyboard controller.
1-3-2-1 Set ES segment to register to 4 GB.
1-3-3-1 Autosize DRAM.
1-3-3-3 Clear 512 K base RAM.
1-3-4-1 Test 512 base address lines.
1-3-4-3 Test 512 K base memory
1-4-1-3 Test CPU bus clock frequency.
1-4-2-4 Reinitialize the chipset.
1-4-3-1 Shadow system BIOS ROM.
1-4-3-2 Reinitialize the cache.
1-4-3-3 Autosize cache.
1-4-4-1 Configure advanced chipset registers.
1-4-4-2 Load alternate registers with CMOS (complementary metal-oxide semiconductor) values.
2-1-1-1 Set initial CPU speed.
2-1-1-3 Initialize interrupt vectors.
2-1-2-1 Initialize BIOS interrupts.
2-1-2-3 Check ROM Copyright notice.
2-1-2-4 Initialize manager for PCI (Peripheral Component Interconnect) options ROMs.
2-1-3-1 Check video configuration against CMOS.
2-1-3-2 Initialize PCI bus and devices.
2-1-3-3 Initialize all video adapters in system.
2-1-4-1 Shadow video BIOS ROM.
2-1-4-3 Display Copyright notice.
2-2-1-1 Display CPU type and speed.
2-2-1-3 Test keyboard.
2-2-2-1 Set key click if enabled.
2-2-2-3 Enable keyboard.
2-2-3-1 Test for unexpected interrupts.
2-2-3-3 Display prompt Press F2 to enter SETUP.
2-2-4-1 Test RAM between 512 and 640 k.
2-3-1-1 Test expanded memory.
2-3-1-3 Test extended memory address lines.
2-3-2-1 Jump to UserPatch1.
2-3-2-3 Configure advanced cache registers.
2-3-3-1 Enable external and CPU caches.
2-3-3-3 Display external cache size.
2-3-4-1 Display shadow message.
2-3-4-3 Display non-disposable segments.
2-4-1-1 Display error messages.
2-4-1-3 Check for configuration errors.
2-4-2-1 Test real-time clock.
2-4-2-3 Check for keyboard errors.
2-4-4-1 Set up hardware interrupts vectors.
2-4-4-3 Test coprocessor if present.
3-1-1-1 Disable onboard I/O ports.
3-1-1-3 Detect and install external RS232 ports.
3-1-2-1 Detect and install external parallel ports.
3-1-2-3 Re-initialize onboard I/O ports.
3-1-3-1 Initialize BIOS data area.
3-1-3-3 Initialize extended BIOS data area.
3-1-4-1 Initialize floppy controller.
3-2-1-1 Initialize hard disk controller.
3-2-1-2 Initialize local bus hard disk controller.
3-2-1-3 Jump to UserPatch2.
3-2-2-1 Disable A20 address line.
3-2-2-3 Clear huge ES segment register.
3-2-3-1 Search for option ROMs.
3-2-3-3 Shadow option ROMs.
3-2-4-1 Set up Power Management.
3-2-4-3 Enable hardware interrupts.
3-3-1-1 Set time of day.
3-3-1-3 Check key lock.
3-3-3-1 Erase F2 prompt.
3-3-3-3 Scan for F2 key stroke.
3-3-4-1 Enter CMOS setup.
3-3-4-3 Clear in POST flag.
3-4-1-1 Check for errors
3-4-1-3 POST done, prepare to boot operating system.
3-4-2-1 One beep.
3-4-2-3 Check password (optional).
3-4-3-1 Clear global descriptor table.
3-4-4-1 Clear parity checkers.
3-4-4-3 Clear screen (optional).
3-4-4-4 Check virus and backup reminders.
4-1-1-1 Try to boot with INT 19.
4-2-1-1 Interrupt handler error.
4-2-1-3 Unknown interrupt error.
4-2-2-1 Pending interrupt error.
4-2-2-3 Initialize option ROM error.
4-2-3-1 Shutdown error.
4-2-3-3 Extended block move.
4-2-4-1 Shutdown 10 error.
4-3-1-3 Initialize the chipset.
4-3-1-4 Initialize refresh counter.
4-3-2-1 Check for forced flash.
4-3-2-2 Check HW status of ROM.
4-3-2-3 BIOS ROM is OK.
4-3-2-4 Do a complete RAM test.
4-3-3-1 Do OEM (original equipment manufacturer) initialization.
4-3-3-2 Initialize interrupt controller.
4-3-3-3 Read in bootstrap code.
4-3-3-4 Initialize all vectors.
4-3-4-1 Boot the flash program.
4-3-4-2 Initialize the boot device.
4-3-4-3 Boot code was read OK.
Two-tone siren Low CPU fan speed, voltage level issue.