Dell OptiPlex 990 Mini-Tower Service Manual page 76

Code 3-2-4
Cause Keyboard Controller Test failure
Code
Cause
Code
Cause
Code
Cause
Code
Cause
Code
Cause
Code 3-4-3
Cause Search for video ROM failure
Code
Cause
Code
Cause
Code
Cause
Code 4–2–4
Cause Unexpected interrupt in protected mode
Code 4–3–1
Cause Memory failure above address 0FFFFh
76
3-3-1
NVRAM power loss
3-3-2
NVRAM configuration
3-3-4
Video Memory Test failure
3-4-1
Screen initialization failure
3-4-2
Screen retrace failure
4–2–1
No time tick
4–2–2
Shutdown failure
4–2–3
Gate A20 failure