If the monitor cannot display error messages during the POST, the system may emit a series of beeps that identifies the problem or that can help you identify a faulty component or assembly. The following table lists the beep codes that may be generated during the POST. Most beep codes indicate a fatal error that prevents the system from completing the boot routine until the indicated condition is corrected.
| Beep Code | Error | Probable Causes |
| 1-1-3 | NVRAM write/read failure | Defective system board |
| 1-1-4 | BIOS checksum failure | Faulty BIOS or defective system board |
| 1-2-1 | Programmable interval-timer failure | Defective system board |
| 1-2-2 | DMA initialization failure | Defective system board |
| 1-2-3 | DMA page register write/read failure | Defective system board |
| 1-3-1 | Main-memory refresh verification failure | Faulty or improperly seated DIMM or defective system board |
| 1-3-2 | No memory installed | No memory installed, or faulty or improperly seated DIMM |
| 1-3-3 | Chip or data line failure in the first 64 KB of main memory | Faulty or improperly seated DIMM |
| 1-3-4 | Odd/even logic failure in the first 64 KB of main memory | Faulty or improperly seated DIMM |
| 1-4-1 | Address line failure in the first 64 KB of main memory | Faulty or improperly seated DIMM |
| 1-4-2 | Parity failure in the first 64 KB of main memory | Faulty or improperly seated DIMM Address line failure in the first 64 KB of RAM (System riser cards may cause this error. Remove the riser card and retest) |
| 2-1-1 through 2-4-4 | Bit failure in the first 64 KB of main memory | Faulty or improperly seated DIMM |
| 3-1-1 | Slave DMA-register failure | Defective system board |
| 3-1-2 | Master DMA-register failure | Defective system board |
| 3-1-3 | Master interrupt-mask register failure | Defective system board |
| 3-1-4 | Slave interrupt-mask register failure | Defective system board |
| 3-2-4 | Keyboard-controller test failure | Faulty keyboard controller (defective system board) |
| 3-3-4 | Screen initialization failure | Faulty video subsystem (defective system board) |
| 3-4-1 | Screen-retrace test failure | Faulty video subsystem (defective system board) |
| 3-4-2 | Search for video ROM failed | Faulty video subsystem (defective system board) |
| 4-2-1 | No timer tick | Defective system board |
| 4-2-2 | Shutdown failure | Defective system board |
| 4-2-3 | Gate A20 failure | Defective system board |
| 4-2-4 | Unexpected interrupt in protected mode | Defective system board |
| 4-3-1 | Memory failure above address 0FFFFh | Faulty or improperly seated DIMM |
| 4-3-3 | Timer-chip counter 2 failure | Defective system board |
| 4-3-4 | Time-of-day clock stopped | Bad battery or defective system board |
| 4-4-1 | Serial-port test failure | Faulty I/O chip (defective system board) |
| 4-4-2 | Parallel-port test failure | Faulty I/O chip (defective system board) |
| 4-4-3 | Math coprocessor failure | Faulty microprocessor chip or system board |
| 4-4-4 | Cache test failure | Defective microprocessor or system board |