IBM BIOS beep codes

POST ABCs

The computer POST (Power On Self Test) tests the computer, insuring that it meets the necessary system requirements and that all hardware is working properly before starting the remainder of the boot process. If the computer passes the POST the computer will have a single beep (with some computer BIOS manufacturers it may beep twice) as the computer starts and the computer will continue to start normally. However, if the computer fails the POST, the computer will either not beep at all or will generate a beep code, which tells the user the source of the problem.

The steps of a POST

Each time the computer boots up the computer must past the POST. Below is the common steps a POST performs each time your computer starts.

1. Test the power supply to ensure that it is turned on and that it releases its reset signal.
2. CPU must exit the reset status mode and thereafter be able to execute instructions.
3. BIOS checksum must be valid, meaning that it must be readable.
4. CMOS checksum must be valid, meaning that it must be readable.
5. CPU must be able to read all forms of memory such as the memory controller, memory bus, and memory module.
6. The first 64KB of memory must be operational and have the capability to be read and written to and from, and capable of containing the POST code.
7. I/O bus / controller must be accessible.
8. I/O bus must be able to write / read from the video subsystem and be able to read all video RAM.

If the computer does not pass any of the above tests, your computer will receive an irregular POST. An irregular POST is a beep code that is different from the standard one or two beeps. This could be either no beeps at all or a combination of different beeps indicating what is causing the computer not to past the POST.

If you're receiving an irregular POST document CH000607 contains all the steps a user can do to resolve the issue or help determine what hardware has failed in the computer so it can be replaced. If you're getting a beep code the remainder of this page contains a listing of each of the major manufacturers beep codes and what they each mean.

IBM BIOS beep codes

Below are 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	Document
No Beeps	No Power, Loose Card, or Short.	CH000312
1 Short Beep	Normal POST, computer is ok.	No problem
2 Short Beep	POST error, review screen for error code.	See screen
Continuous Beep	No Power, Loose Card, or Short.	CH000607
Repeating Short Beep	No Power, Loose Card, or Short.	CH000607
One Long and one Short Beep	Motherboard issue.	CH000607
One Long and Two Short Beeps	Video (Mono/CGA Display Circuitry) issue.	CH000607
One Long and Three Short Beeps.	Video (EGA) Display Circuitry.	CH000607
Three Long Beeps	Keyboard / Keyboard card error.	CH000304
One Beep, Blank or Incorrect Display	Video Display Circuitry.	CH000607

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