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Due to the amount of beep codes a PC can give, there are many questions on Super User about beep codes! I'm hoping this post will help to provide a community answer about all (dare I say all?) beep codes, with my fictional question.

When I try to turn my PC on, I hear some beeps. This is not beeping from the HDD or fan, but from the motherboard. Regardless of the number of beeps, what do the beeps mean?

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I'm attempting to create a canonical question as per this meta question. Feel free to add any other questions that I can reference/we can close, add tags, or edit either the question or answer to improve on it, or to post answers. –  Dave Aug 14 '14 at 13:48

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The beeps are commonly referred to as beep codes. They provide an indication, usually about state of some hardware.

A beep code is the audio signal given out by a computer to announce the result of a short diagnostic testing sequence the computer performs when first powering up (called the Power-On-Self-Test or POST ). The POST is a small program contained in the computer's Basic Input/Output Operating System ( BIOS ) that checks to make sure necessary hardware is present and required memory is accessible. If everything tests out correctly, the computer will typically emit a single beep and continue the starting-up process. If something is wrong, the computer will display an error message on the monitor screen and announce the errors audibly with a series of beeps that vary in pitch, number and duration (this is especially useful when the error exists with the monitor or graphic components). The beeping sequence is really a coded message (beep code) designed to tell the user what is wrong with the computer.

There is no official standard for beep codes; audio patterns vary according to the manufacturer of the computer's BIOS program. If an error message is beeped on startup, the user must first determine what kind of BIOS the computer is running (Phoenix or AMI are the most popular) and use that information to look up the particular beep code sequence that is being sent. BIOS information and beep code interpretations can be found in the manual that comes with the computer and on the manufacturer's Web site.

Source

So, to understand it, the first thing you need to do is find out what BIOS you have (this can be achieved by reading the manual. If you don't have one, the manufacturer usually keeps an electronic copy on their site. Also see Find out what the motherboard on my computer is

Now, the beep codes:

AMI BIOS beep codes

Below are the AMI BIOS Beep codes that can occur. However, because of the wide variety of different computer manufacturers with this BIOS, the beep codes may vary.
Beep Code             Descriptions
1 short               DRAM refresh failure
2 short               Parity circuit failure
3 short               Base 64K RAM failure
4 short               System timer failure
5 short               Processor failure
6 short               Keyboard controller Gate A20 error
7 short               Virtual mode exception error
8 short               Display memory Read/Write test failure
9 short               ROM BIOS checksum failure
10 short              CMOS shutdown Read/Write error
11 short              Cache Memory error
1 long, 3 short       Conventional/Extended memory failure
1 long, 8 short       Display/Retrace test failed


AWARD BIOS beep codes

Below are Award BIOS Beep codes that can occur. 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           Indicates a video error has occurred and the BIOS cannot initialize the video screen to display any additional information
Any other beep(s)         RAM problem.

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


IBM BIOS beep codes

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

Beep Code                               Description
No Beeps                                No Power, Loose Card, or Short.
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.
One Long and one Short Beep             Motherboard issue.
One Long and Two Short Beeps            Video (Mono/CGA Display Circuitry) issue.
One Long and Three Short Beeps.         Video (EGA) Display Circuitry.
Three Long Beeps                        Keyboard or Keyboard card error.
One Beep, Blank or Incorrect Display    Video Display Circuitry.


Macintosh startup tones

Tones                                       Error
Error Tone. (two sets of different tones)   Problem with logic board or SCSI 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.


Phoenix BIOS beep codes

Below are the beep codes for Phoenix BIOS Q3.07 OR 4.X
Beep Code             Description and what to check
1-1-1-3               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 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               28 Autosize DRAM.
1-3-3-3               Clear 512K base RAM.
1-3-4-1               Test 512 base address lines.
1-3-4-3               Test 512K 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 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 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               56 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 640k.
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 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 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.

Source

Update

AMI UEFI beep codes

Beep code          Description        Debug code
No beep            Bad CPU            No debug code
No beep            Bad memory         45
3 long beeps       Without memory     53
No beep(no power)  Without CPU        No debug code
5 long beeps       Without VGA card   Beeps at”d6”, then show "0d"

Source

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