When you power on a computer the BIOS immediately takes control of the computer and performs the P.O.S.T (Power On Self Test). At the end of the POST the computer will play an audible 'BEEP' through either the PC's internal speaker of through speakers attached to the sound card (if you have a built-in sound chip). If the POST completed successfully without detecting any problems with then system will play a single short beep to let you know the test is complete and the computer will continue to startup and load the operating system.
If during the POST the BIOS detects a problem it will normally display a visual error message on the monitor explaining what the problem is. However, if a problem is detected before the BIOS initializes the video card, or a video card is not present or not detected then the BIOS will play several 'BEEPS' through the speaker to let you know there is a problem. Depending on the type of the BIOS you have the BIOS may play beeps in a specific pattern to indicate what the problem is, or play the same beep a number of times indicating the problem. It is very important that you pay close attention to the number and/or pattern of the beeps your computer plays on startup.
Below is a Tip n Tricks table of the most common AMI, Phoenix and Award BIOS beep codes.
AMI (American Megatrends International) BIOS Beep Codes.
AMI BIOS uses beeps of the same length and pitch. The error is displayed as a number of beeps. For example, 4 beeps indicated a timer failure.
Click image to enlarge:
Award BIOS Beep Codes
Award BIOS uses beeps of varying duration. A long beep will typically last for 2 seconds while a short beep will last only 1 second. Award BIOS also uses beeps of different frequency to indicate critical errors. If an Award BIOS detects that the CPU is overheating it may play a high pitched repeating beep while the computer is running.
Click image to enlarge:
Phoenix BIOS Beep Codes
Phoenix BIOS uses beep code patterns to indicate problems. In the table below the '-' indicates a brief pause between beeps. Example: 1 - 1 - 2 would sound like BEEP BEEP BEEP BEEP
Click image to enlarge:
