Dell OptiPlex 755 Quick Reference Manual page 71

Code
1-3-1 through
2-4-4
4-3-1
If you experience any of the following beep code errors, see "Contacting Dell"
in the User's Guide
Code
1-1-2
1-1-3
1-1-4
1-2-1
1-2-2
1-2-3
1-3
1-3-1 through
2-4-4
3-1-1
3-1-2
3-1-3
3-1-4
3-2-2
3-2-4
3-3-1
3-3-2
3-3-4
3-4-1
3-4-2
3-4-3
Cause
Memory not being properly identified or used
Memory failure above address 0FFFFh
for instructions on obtaining technical assistance.
Cause
Microprocessor register failure
NVRAM read/write failure
ROM BIOS checksum failure
Programmable interval timer failure
DMA initialization failure
DMA page register read/write failure
Video Memory Test failure
Memory not being properly identified or used
Slave DMA register failure
Master DMA register failure
Master interrupt mask register failure
Slave interrupt mask register failure
Interrupt vector loading failure
Keyboard Controller Test failure
NVRAM power loss
Invalid NVRAM configuration
Video Memory Test failure
Screen initialization failure
Screen retrace failure
Search for video ROM failure
Quick Reference Guide
71