No Signal on Monitor After Building PC: Verify Display Cable to GPU
A technician built a new desktop computer. When the power button is pressed, all fans spin and the case LEDs light up, but the monitor shows 'No Signal'. The technician has verified that the monitor works with another computer. Which of the following should the technician do FIRST?
Quick Answer
The correct first step is to ensure the monitor cable is connected to the discrete GPU instead of the motherboard. This is because modern CPUs often lack integrated graphics, or the motherboard automatically disables the integrated graphics when a discrete GPU is detected, so plugging into the motherboard’s video port will produce a “no signal on monitor after building PC” error even though all fans spin and LEDs light up. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your understanding of display output routing and is a common trap—many new technicians mistakenly connect to the motherboard first, assuming it will work. A reliable memory tip is “GPU gets the plug”: if a discrete graphics card is installed, always connect the display cable to the GPU’s ports, not the motherboard’s.
⚠ Common exam trap
CompTIA often tests the misconception that all CPUs have integrated graphics, leading candidates to assume the motherboard video port is always functional, when in reality many modern CPUs require a discrete GPU for display output.
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
✓
Ensure the monitor cable is connected to the discrete GPU instead of the motherboard
The correct first step is to ensure the monitor cable is connected to the discrete GPU rather than the motherboard. Modern CPUs often lack integrated graphics, or the motherboard may disable the integrated graphics when a discrete GPU is installed. Connecting to the motherboard's video port would result in a 'No Signal' error because the system is outputting video through the discrete GPU.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reseat the RAM modules
Why it's wrong here
Reseating RAM addresses intermittent memory seating faults, yet the fans and LEDs already confirm power delivery; a POST failure from unseated RAM typically yields beep codes or no display with diagnostic indication. It is tempting as a quick first step, but checking display cabling to the correct GPU output precedes it.
When this WOULD be correct
If the computer powers on (fans spin, LEDs on) but the monitor shows 'No Signal' and the system does not beep or show any signs of POST (e.g., no keyboard lights), reseating RAM is a correct first step because improperly seated RAM can prevent POST and video output.
- ✓
Ensure the monitor cable is connected to the discrete GPU instead of the motherboard
Why this is correct
With a discrete GPU installed, the motherboard's video outputs are typically disabled, so the monitor receives no signal despite the system powering on. Connecting the cable to the graphics card's port restores output, making this the quickest check before reseating components.
- ✗
Replace the power supply with a higher wattage unit
Why it's wrong here
The power supply provides sufficient electricity because the fans and LEDs are operational, meaning the issue lies in a data transmission failure rather than insufficient wattage. Upgrading the unit is intended to prevent system shutdowns during high-load tasks, such as when adding a high-performance GPU that exceeds current amperage limits. In this scenario, increasing capacity will not resolve the lack of video output caused by faulty RAM or an improperly seated graphics card.
When this WOULD be correct
This would be correct if the system fails to power on at all (no fans, no LEDs) or if it randomly shuts down under load, indicating insufficient or failing power supply.
- ✗
Reinstall the CPU and check for bent pins
Why it's wrong here
Reinstalling the CPU and inspecting socket pins is invasive and risks further damage; bent pins usually prevent POST entirely, often with no fan spin. It is tempting when a build shows no display, but verifying the monitor cable connects to the discrete GPU output is the faster first check.
When this WOULD be correct
If the system powers on but does not POST (no beeps, no display, fans spin but no activity), and the technician has already verified other components, reseating or inspecting the CPU for bent pins would be appropriate. This is common after a CPU replacement or if the system was shipped.
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.
✓Ensure the monitor cable is connected to the discrete GPU instead of the motherboardCorrect answer▾
Why this is correct
With a discrete GPU installed, the motherboard's video outputs are typically disabled, so the monitor receives no signal despite the system powering on. Connecting the cable to the graphics card's port restores output, making this the quickest check before reseating components.
✗Reseat the RAM modulesWrong answer — click to see why▾
Why this is wrong here
The fans spin and LEDs light up, indicating power delivery is likely sufficient. The monitor works with another computer, so the issue is with the video output path. Reseating RAM would not affect the video signal if the system is already posting (fans spin).
★ When this WOULD be the correct answer
If the computer powers on (fans spin, LEDs on) but the monitor shows 'No Signal' and the system does not beep or show any signs of POST (e.g., no keyboard lights), reseating RAM is a correct first step because improperly seated RAM can prevent POST and video output.
Why candidates choose this
Candidates often default to reseating RAM as a universal troubleshooting step for 'No Signal' issues because RAM problems are common and can cause boot failures, but here the system appears to power on normally, making it less likely.
✗Replace the power supply with a higher wattage unitWrong answer — click to see why▾
Why this is wrong here
The system has power (fans spin, LEDs light), so the PSU is likely sufficient. A higher wattage unit would not fix a 'No Signal' issue caused by incorrect video output connection.
★ When this WOULD be the correct answer
This would be correct if the system fails to power on at all (no fans, no LEDs) or if it randomly shuts down under load, indicating insufficient or failing power supply.
Why candidates choose this
Candidates may assume that a new build with a discrete GPU requires more power, and that a weak PSU could cause display issues, even though the system clearly has power.
✗Reinstall the CPU and check for bent pinsWrong answer — click to see why▾
Why this is wrong here
The CPU is already installed and the system powers on (fans spin, LEDs light), indicating the CPU is likely seated correctly. Bent pins would typically prevent POST entirely, not just video output, so this is not the first step.
★ When this WOULD be the correct answer
If the system powers on but does not POST (no beeps, no display, fans spin but no activity), and the technician has already verified other components, reseating or inspecting the CPU for bent pins would be appropriate. This is common after a CPU replacement or if the system was shipped.
Why candidates choose this
Candidates may assume that a 'No Signal' issue is always a CPU or motherboard problem, especially if they have encountered bent pins in the past, and overlook the simpler video connection issue.
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
About these practice questions
This 220-1101 question is part of Courseiva's 896-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is upgrading a desktop computer with a new dedicated graphics card. After installation, the computer powers on, the GPU fans spin, but the monitor displays a 'No Signal' message. The monitor is known to be working, and the technician has confirmed the card is properly seated in the PCIe x16 slot and the PCIe power connectors are securely attached. Which of the following should the technician check NEXT?
easy- A.Replace the GPU in a different PCIe slot
- ✓ B.Verify the display cable is connected to the GPU and not the motherboard
- C.Update the motherboard BIOS to the latest version
- D.Replace the power supply with a higher wattage unit
Why B: The most common reason for a 'No Signal' message after installing a dedicated GPU is that the display cable is still connected to the motherboard's integrated graphics port instead of the new GPU's output ports. The motherboard's video outputs are typically disabled when a discrete GPU is detected, so the monitor receives no signal from that source. Since the GPU fans spin and power connections are secure, the next logical step is to verify the physical display connection.
JA
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.