Dell OptiPlex N Service Manual (.pdf) - Page 37

Table 3-1. POST Beep Codes (continued) Beep Code Error Probable Causes 3-2-4 Keyboard-controller test failure Faulty keyboard controller (defective system board) 3-3-4 3-4-1 Screen initialization failure Screen-retrace test failure Faulty video subsystem (defective system board) 3-4-2 4-2-1 Search for video ROM failure No timer tick Defective system board 4-2-2 Shutdown failure 4-2-3 Gate A20 failure 4-2-4 4-3-1 4-3-3 4-3-4 4-4-1 4-4-2 4-4-3 4-4-4 Unexpected interrupt in protected mode Memory failure above address 0FFFFh Timer-chip counter 2 failure Time-of-day clock stopped Serial-port test failure Parallel-port test failure Math coprocessor failure Cache test failure Faulty or improperly seated DIMM Defective system board Bad battery or defective system board Faulty I/O chip (defective system board) Faulty microprocessor chip or system board Defective microprocessor or system board Beep Codes and Error Messages 3-3