Dell OptiPlex 755 - Manual (Page 210)

Beep Codes
Your computer might emit a series of beeps during start-up if the monitor cannot display errors or problems. This series of beeps, called a beep code, identifies
a problem. For example, beep code 1-3-1 (one possible beep code) consists of one beep, a burst of three beeps, and then one beep. This beep code tells you
that the computer encountered a memory problem.
Reseating the memory modules may correct the following beep code errors. If the problem persists, contact Dell (see Contacting Dell ) for instructions on
obtaining technical assistance.
If you experience any of the following beep code errors, see Contacting Dell for instructions on obtaining technical assistance.
System Messages
Code Cause
1-3-1 through 2-4-4 Memory not being properly identified or used
4-3-1 Memory failure above address 0FFFFh
Code Cause
1-1-2 Microprocessor register failure
1-1-3 NVRAM read/write failure
1-1-4 ROM BIOS checksum failure
1-2-1 Programmable interval timer failure
1-2-2 DMA initialization failure
1-2-3 DMA page register read/write failure
1-3 Video Memory Test failure
1-3-1 through 2-4-4 Memory not being properly identified or used
3-1-1 Slave DMA register failure
3-1-2 Master DMA register failure
3-1-3 Master interrupt mask register failure
3-1-4 Slave interrupt mask register failure
3-2-2 Interrupt vector loading failure
3-2-4 Keyboard Controller Test failure
3-3-1 NVRAM power loss
3-3-2 Invalid NVRAM configuration
3-3-4 Video Memory Test failure
3-4-1 Screen initialization failure
3-4-2 Screen retrace failure
3-4-3 Search for video ROM failure
4-2-1 No timer tick
4-2-2 Shutdown failure
4-2-3 Gate A20 failure
4-2-4 Unexpected interrupt in protected mode
4-3-1 Memory failure above address 0FFFFh
4-3-3 Timer-chip counter 2 failure
4-3-4 Time-of-day clock stopped
4-4-1 Serial or parallel port test failure
4-4-2 Failure to decompress code to shadowed memory
4-4-3 Math-coprocessor test failure
4-4-4 Cache test failure
NOTE: If the message you received is not listed in the table, see the documentation for either the operating system or the program that was running
when the message appeared.
Message Possible Cause Corrective Action
8042 Gate-A20
error
The keyboard controller
failed its test. If you receive this message after you make
changes in the system setup program, enter
the system setup program and restore the
original value(s).
Address Line An error in the address Reseat the memory modules (see Memory ).