AMI BIOS Beep Codes: One Long Three Short
A technician is troubleshooting a workstation that emits one long beep followed by two short beeps during POST. The monitor shows no display. The technician has tested the dedicated GPU in another system where it worked, and has reseated all power cables and RAM. Which of the following should the technician try NEXT?
⚠ Common exam trap
CompTIA often tests the candidate's ability to interpret POST beep codes correctly; the trap here is that candidates may assume a video-related beep always means the GPU is bad, ignoring that the GPU was already verified working, and instead jump to replacing the motherboard or power supply without first resetting the BIOS settings.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
C. Clear the CMOS
The one long beep followed by two short beeps during POST is a standard AMI BIOS code indicating a video adapter failure. Since the dedicated GPU was tested and works in another system, and RAM has been reseated, the issue is likely a corrupted or misconfigured BIOS/UEFI setting (e.g., incorrect video initialization order or a stuck memory hole). Clearing the CMOS resets these settings to factory defaults, which can resolve the POST error without replacing hardware.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A. Replace the motherboard
Why it's wrong here
Replacing the motherboard is premature as the one long, two short beep code specifically indicates a video subsystem issue, not a general motherboard fault. Given the dedicated GPU works elsewhere, the next step should target the *onboard* video output, *BIOS settings*, or the *PCIe slot* itself, rather than replacing the entire board. This option is tempting because a faulty motherboard can cause POST failures and no display, making it a correct solution when all other components are verified functional and diagnostics point to a core board problem.
When this WOULD be correct
If the technician had confirmed that the motherboard fails POST with no beeps or with continuous beeps, and all other components (CPU, RAM, GPU, PSU) tested functional in another system, then replacing the motherboard would be the correct next step.
- ✗
B. Replace the power supply
Why it's wrong here
Replacing the power supply is a shotgun repair that is not supported by the symptoms: the workstation powers on, the motherboard receives power, and the processor initializes far enough to produce POST status beeps. A failing PSU would typically manifest as complete power loss, random shutdowns under load, or repeated power-on loops, not a stable video error beep after the system has already powered up. The fact that the existing supply is able to deliver sustained power to the CPU, chipset, and motherboard during the POST sequence strongly indicates that voltage levels are within specification, so replacing it would not resolve the video subsystem fault indicated by the beep code.
When this WOULD be correct
A workstation fails to power on with no beeps or POST, and a multimeter shows low voltages on the PSU outputs. Replacing the power supply would be the next step.
- ✓
C. Clear the CMOS
Why this is correct
The one-long, two-short beep sequence specifically indicates a video subsystem error, and a corrupted or misconfigured BIOS setting—such as the primary display adapter incorrectly set to PCIe or PEG when the monitor is connected to onboard video—can produce this error. Clearing the CMOS via the motherboard jumper, onboard button, or temporarily removing the battery resets these volatile BIOS settings to factory defaults, forcing the system to re-enumerate video devices on the next POST. Because the dedicated GPU is known to work in another system, the fault likely lies in the configuration or the onboard video path, making CMOS reset the safest, least invasive corrective action.
- ✗
D. Test the RAM in another system
Why it's wrong here
The beep code generated during POST does not indicate a memory error; RAM faults typically produce different patterns, such as a repeating short beep, a continuous long beep, or a specific memory-count beep sequence depending on the BIOS vendor. Additionally, reseating the memory modules has already been performed as a preliminary step, and moving the RAM to another system is an unnecessary diagnostic action that cannot address a video initialization failure. Since the system is clearly executing POST—evidenced by the beep itself—the memory subsystem is sufficiently functional to reach the video error stage, and memory testing would neither confirm nor rule out the actual cause.
When this WOULD be correct
This option would be correct in a scenario where the workstation emits a repeating short beep pattern (indicating a RAM error) and the technician has already reseated the RAM. Testing the RAM in another system would help isolate whether the RAM module itself is faulty.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓C. Clear the CMOSCorrect answer▾
Why this is correct
The one-long, two-short beep sequence specifically indicates a video subsystem error, and a corrupted or misconfigured BIOS setting—such as the primary display adapter incorrectly set to PCIe or PEG when the monitor is connected to onboard video—can produce this error. Clearing the CMOS via the motherboard jumper, onboard button, or temporarily removing the battery resets these volatile BIOS settings to factory defaults, forcing the system to re-enumerate video devices on the next POST. Because the dedicated GPU is known to work in another system, the fault likely lies in the configuration or the onboard video path, making CMOS reset the safest, least invasive corrective action.
✗A. Replace the motherboardWrong answer — click to see why▾
Why this is wrong here
The dedicated GPU works in another system, and reseating power cables and RAM didn't resolve the issue. The beep code (one long, two short) typically indicates a video or display problem, but since the GPU is functional, the issue is likely with the motherboard's BIOS or CMOS settings, not a hardware failure requiring motherboard replacement.
★ When this WOULD be the correct answer
If the technician had confirmed that the motherboard fails POST with no beeps or with continuous beeps, and all other components (CPU, RAM, GPU, PSU) tested functional in another system, then replacing the motherboard would be the correct next step.
Why candidates choose this
Candidates may assume that a no-display issue with a beep code pointing to video means the motherboard is faulty, especially after verifying the GPU works elsewhere, but they overlook the possibility of a corrupted BIOS or CMOS settings that can be fixed by clearing CMOS.
✗B. Replace the power supplyWrong answer — click to see why▾
Why this is wrong here
The power supply is unlikely to cause a specific beep code (1 long, 2 short) indicating a video error, and the GPU works in another system, so power delivery is not the issue.
★ When this WOULD be the correct answer
A workstation fails to power on with no beeps or POST, and a multimeter shows low voltages on the PSU outputs. Replacing the power supply would be the next step.
Why candidates choose this
Candidates may attribute any POST failure to power issues, especially after reseating cables, without recognizing that beep codes point to specific hardware faults.
✗D. Test the RAM in another systemWrong answer — click to see why▾
Why this is wrong here
The RAM has already been reseated, and the beep code (1 long, 2 short) indicates a video or display issue, not a RAM problem. Testing RAM in another system would not address the likely cause of the POST failure.
★ When this WOULD be the correct answer
This option would be correct in a scenario where the workstation emits a repeating short beep pattern (indicating a RAM error) and the technician has already reseated the RAM. Testing the RAM in another system would help isolate whether the RAM module itself is faulty.
Why candidates choose this
Candidates may think that since the GPU was tested and works, the issue must be with another component like RAM, and testing RAM in another system is a common troubleshooting step for memory-related problems.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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GPUs and Display Technologies
Key term
Complementary Metal-Oxide Semiconductor
A type of semiconductor technology used in microchips that combines two types of transistors to create circuits with very low power consumption.
Key term
RAM
RAM (Random-Access Memory) is volatile computer memory that temporarily stores data for quick access by the CPU.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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