Troubleshooting a PC That Powers On But Shows No Signal
A technician is troubleshooting a desktop computer that powers on (fans spin, lights turn on) but the monitor displays 'No Signal'. The technician has already verified that the monitor works on another computer and has reseated the RAM and the discrete GPU. The motherboard has integrated graphics. Which of the following should the technician do NEXT?
⚠ Common exam trap
It's easy for candidates to assume a 'No Signal' error always points to RAM or PSU issues, but the fact that the system powers on and the monitor works elsewhere narrows the fault to the GPU or its connection, making the integrated graphics test the most efficient next step.
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
✓
Remove the discrete GPU and connect the monitor to the integrated graphics port.
Since the monitor works on another computer and the RAM/GPU have been reseated, the next logical step is to isolate whether the discrete GPU is faulty. By removing the discrete GPU and connecting the monitor to the integrated graphics port, the technician can test if the system boots with the CPU's built-in graphics. If it does, the discrete GPU is likely the problem; if not, the issue lies elsewhere (e.g., motherboard or CPU).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace the power supply unit (PSU) with a known-working unit.
Why it's wrong here
A faulty PSU can certainly prevent video output, but the fact that the system powers on and case fans spin indicates the power supply is delivering at least the primary +12V and +5V rails. PSU failures typically manifest as no power, random shutdowns, or an inability to handle load, not as a clean 'No Signal' with an otherwise running system. Swapping the PSU is time-consuming and should be reserved for after eliminating the display adapter and its connections. Additionally, modern motherboards with on-board diagnostics can often pinpoint a power delivery issue before resorting to a full PSU replacement, making this step premature.
When this WOULD be correct
If the computer does not power on at all (no fans, no lights), and a known-working PSU restores power, then replacing the PSU would be correct. This scenario isolates a dead PSU.
- ✗
Clear the CMOS by removing the onboard battery for 30 seconds.
Why it's wrong here
Clearing CMOS by removing the onboard battery resets BIOS/UEFI settings to defaults, which could theoretically fix a misconfigured display output option, but the most common cause of a 'No Signal' on a system with a discrete GPU is the GPU itself or its cabling. The issue here is more likely hardware-related, as a stuck BIOS setting would usually still produce a POST beep sequence or the integrated graphics would activate automatically. Clearing CMOS is a blanket reset that wipes fan curves, boot order, and overclock settings, so it is better to use a targeted hardware isolation step first. Furthermore, if the system was working previously, the BIOS settings are probably not the culprit; a failed GPU is a far more common scenario.
When this WOULD be correct
Clearing CMOS would be the next step if the system had a black screen after changing BIOS settings (e.g., overclocking, boot order) or if the system was not posting due to incorrect memory timings, and other hardware was verified working.
- ✓
Remove the discrete GPU and connect the monitor to the integrated graphics port.
Why this is correct
Removing the discrete GPU and connecting the monitor to the integrated graphics port directly tests whether the video output failure originates from the add-in card. If the system posts and displays video using the iGPU, the discrete GPU is almost certainly faulty, improperly seated, or has a bad power connection. This isolation step is the most efficient next action because it bypasses the suspected component entirely. Note that this test only works if the CPU and motherboard support integrated graphics; otherwise, a known-good GPU or a system speaker diagnostic is needed.
- ✗
Replace the RAM modules with known-working ones.
Why it's wrong here
RAM faults can cause a blank screen, but they usually also produce audible beep codes or a boot loop as the POST routine fails early. In this scenario, the fans are spinning and no beep codes are mentioned, which suggests the motherboard is receiving power and the CPU is executing code, making RAM failure less likely. Since the RAM has already been reseated and the symptoms point to a video output path, swapping RAM modules introduces an unnecessary variable and does not isolate the most probable cause. A more targeted test would be using the integrated graphics port before replacing hardware.
When this WOULD be correct
A technician is troubleshooting a computer that powers on but has no display, and all other components (including GPU and monitor) have been verified working. The technician has not yet reseated or tested the RAM. In that scenario, replacing RAM with known-working modules would be a logical next step to rule out faulty RAM.
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.
✓Remove the discrete GPU and connect the monitor to the integrated graphics port.Correct answer▾
Why this is correct
Removing the discrete GPU and connecting the monitor to the integrated graphics port directly tests whether the video output failure originates from the add-in card. If the system posts and displays video using the iGPU, the discrete GPU is almost certainly faulty, improperly seated, or has a bad power connection. This isolation step is the most efficient next action because it bypasses the suspected component entirely. Note that this test only works if the CPU and motherboard support integrated graphics; otherwise, a known-good GPU or a system speaker diagnostic is needed.
✗Replace the power supply unit (PSU) with a known-working unit.Wrong answer — click to see why▾
Why this is wrong here
The PSU is not the likely cause because the computer powers on (fans spin, lights on), indicating the PSU is delivering power. The issue is video output, not power delivery.
★ When this WOULD be the correct answer
If the computer does not power on at all (no fans, no lights), and a known-working PSU restores power, then replacing the PSU would be correct. This scenario isolates a dead PSU.
Why candidates choose this
Candidates may think a failing PSU can cause intermittent issues like no video, but the symptoms here (fans and lights working) strongly suggest the PSU is functional.
✗Clear the CMOS by removing the onboard battery for 30 seconds.Wrong answer — click to see why▾
Why this is wrong here
Clearing CMOS resets BIOS settings but does not resolve a 'No Signal' issue caused by the system defaulting to the discrete GPU, which may be faulty. The monitor is known working, and the discrete GPU is the likely culprit.
★ When this WOULD be the correct answer
Clearing CMOS would be the next step if the system had a black screen after changing BIOS settings (e.g., overclocking, boot order) or if the system was not posting due to incorrect memory timings, and other hardware was verified working.
Why candidates choose this
Candidates may think clearing CMOS is a universal fix for boot issues, especially when hardware reseating fails, but it does not address the specific symptom of 'No Signal' with a working monitor.
✗Replace the RAM modules with known-working ones.Wrong answer — click to see why▾
Why this is wrong here
The technician has already reseated the RAM, and the system powers on with fans and lights, indicating the PSU is likely functional. Replacing RAM is premature without first isolating whether the discrete GPU is causing the display issue, especially since integrated graphics are available.
★ When this WOULD be the correct answer
A technician is troubleshooting a computer that powers on but has no display, and all other components (including GPU and monitor) have been verified working. The technician has not yet reseated or tested the RAM. In that scenario, replacing RAM with known-working modules would be a logical next step to rule out faulty RAM.
Why candidates choose this
Candidates may think that since the system powers on but has no display, the RAM could be faulty, and replacing it is a common troubleshooting step. They overlook that reseating RAM was already done and that the discrete GPU is a more likely culprit given the available integrated graphics.
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?”
Go deeper
Related to this question
Learn chapter
Motherboard Components and Form Factors
Key term
RAM
RAM (Random-Access Memory) is volatile computer memory that temporarily stores data for quick access by the CPU.
Key term
Dual In-line Memory Module
A Dual In-line Memory Module (DIMM) is a small circuit board that holds memory chips and plugs into a computer's motherboard to provide Random Access Memory (RAM).
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.