220-1201 Core PC Hardware Troubleshooting — 20 Questions

Question 1

A technician is troubleshooting a PC that boots to a black screen with a blinking cursor after the BIOS screen. The system has a single SSD with the OS installed. The BIOS detects the SSD. What is the most likely cause?

Accepted Answer

The bootloader is corrupted. A black screen with a blinking cursor after POST indicates the BIOS found a bootable device but cannot locate the bootloader. This is often due to a corrupted Master Boot Record (MBR) or GUID Partition Table (GPT). The technician should boot from installation media and use the Startup Repair or bootrec commands to rebuild the bootloader.

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The SSD is not properly formatted

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The RAM is faulty

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The power supply is underpowered

Question 2

A user reports that their PC randomly restarts during boot-up, sometimes before the Windows logo appears. They have already tried reseating the RAM. Which component should be tested next?

Accepted Answer

Test the power supply unit. Random restarts during early boot, especially before the OS loads, often point to a failing power supply. The PSU may not be providing stable voltages under the initial power draw of the system. Using a multimeter to test voltage outputs or swapping with a known-good PSU is the next step.

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Replace the motherboard

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Reinstall the operating system

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Check for BIOS updates

Question 3

A technician is deploying a new SSD in a desktop PC. After installing the drive and connecting the SATA data and power cables, the system does not recognize the drive in the BIOS. All other drives are detected. What should the technician check first?

Accepted Answer

Reseat the SATA data and power cables. When a new drive is not detected, the most common cause is a loose or improper connection. The technician should reseat both the SATA data cable at the drive and motherboard, and the power cable from the PSU. If that fails, testing the drive in another port or with another cable is the next step.

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Update the motherboard BIOS

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Check if the drive needs to be initialized in Disk Management

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Replace the SATA controller

Question 4

A user reports that their PC emits a continuous series of short beeps and will not display anything on the screen. The system was working fine after a recent RAM upgrade. What is the most likely cause of this issue?

Accepted Answer

The new RAM is incompatible or faulty. Continuous short beeps typically indicate a power supply failure or a motherboard power issue. However, given the recent RAM upgrade, it is more likely that the new RAM is incompatible or not seated correctly. The technician should first reseat the RAM and try the original modules to isolate the problem.

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The CPU is overheating

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The graphics card is not seated properly

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The motherboard is shorting against the case

Question 5

A client brings in a desktop that will not power on. The technician verifies the power cord is connected and the PSU fan does not spin when the power button is pressed. What is the most appropriate next step?

Accepted Answer

Test the power supply using a PSU tester. When the PSU fan does not spin, the power supply may be dead. The quickest and safest test is to use a power supply tester or perform the paperclip test to see if the PSU turns on. If it does not, replacement is needed. Always eliminate the PSU as the cause before checking other components.

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Replace the motherboard

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Reseat the CPU

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Check the front panel power switch

Question 6

A technician is configuring a new workstation for video editing. After installing a high-end GPU and additional RAM, the system powers on but the screen is blank. The motherboard has diagnostic LEDs; the VGA LED is lit. What is the most likely issue?

Accepted Answer

Loose GPU power cables. A lit VGA diagnostic LED indicates the motherboard is not detecting the GPU. This is common when the GPU is not fully seated in the PCIe slot or when additional power cables are not connected. The technician should reseat the GPU and ensure all power connectors are attached.

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Incompatible RAM

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Faulty CPU

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Monitor set to wrong input

Question 7

A user complains that their computer randomly shuts down after about 30 minutes of gaming. The case feels warm to the touch, and all fans are spinning. Which component is most likely causing the shutdowns?

Accepted Answer

Overheating CPU or GPU. Random shutdowns under load, especially with a warm case, strongly suggest overheating. The CPU or GPU thermal protection is triggering to prevent damage. Cleaning dust from heatsinks and fans, and ensuring proper airflow, is the first step.

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Failing hard drive

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Insufficient RAM

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Loose power cable

Question 8

A customer reports that their desktop PC emits a series of three long beeps and then nothing appears on the screen. The system was working fine yesterday. What is the most likely cause of this issue?

Accepted Answer

Loose or failed RAM module. Three long beeps during POST typically indicate a memory (RAM) failure. This is a common POST code for many BIOS manufacturers, and reseating or replacing the RAM modules is the first troubleshooting step. The beeps are a diagnostic signal from the motherboard that the system cannot proceed without functional memory.

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Faulty power supply unit

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Overheating CPU

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Corrupted operating system files

Question 9

A technician is troubleshooting a desktop that powers on but displays nothing on the monitor. The monitor is on and connected via HDMI. The technician hears one short beep from the motherboard speaker. What should the technician do next?

Accepted Answer

Reseat the graphics card. One short beep typically indicates a successful POST, meaning the CPU, RAM, and motherboard are likely functional. The issue is therefore probably with the display subsystem: the video card or its connection. The technician should reseat the GPU or try a different video output port.

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Replace the RAM modules

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Test the monitor on another computer

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Flash the BIOS

Question 10

A customer says their laptop battery no longer charges. The laptop works when plugged into AC power, but the battery icon shows '0% available (plugged in)'. What is the most likely cause?

Accepted Answer

Defective battery. When a laptop runs on AC but the battery shows 0% and does not charge, the battery has likely reached the end of its life cycle. Lithium-ion batteries degrade over time and lose capacity; eventually they can no longer hold a charge. The solution is to replace the battery.

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Faulty AC adapter

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Dead CMOS battery

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Corrupted battery driver

Question 11

A user reports that their PC boots to a black screen with a blinking cursor after installing a new SATA SSD. The old hard drive is still connected. What is the most likely issue?

Accepted Answer

The boot order in BIOS is incorrect. The blinking cursor on a black screen usually indicates the system cannot find a bootable device. With two drives connected, the boot order in the BIOS may be set to the old hard drive or the new SSD may not have an OS installed.

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The new SSD is defective

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The SATA cable is loose

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The power supply is insufficient

Question 12

A user's PC is running very slowly, and the hard drive activity LED is constantly lit even when idle. Task Manager shows 100% disk usage. Which component is most likely failing?

Accepted Answer

Failing hard drive. Constant 100% disk usage with no corresponding high CPU or memory usage is a classic sign of a failing hard drive, often due to bad sectors or mechanical wear. While a slow drive can be caused by malware or fragmentation, hardware failure is the primary suspect in this scenario.

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Insufficient RAM

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CPU overheating

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Malware infection

Question 13

After replacing a motherboard, a technician finds that the PC will not power on at all. The power supply fan does not spin, and no LEDs light up. The PSU was working before the replacement. What is the most likely cause?

Accepted Answer

The front panel power switch header is not connected correctly. No power at all after a motherboard swap strongly suggests an electrical connection issue. The most common cause is that the front panel power switch header is not connected correctly to the motherboard, or the PSU is not properly connected to the motherboard.

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The power supply is dead

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The CPU is not compatible with the new motherboard

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The RAM is not seated properly

Question 14

A user reports that their PC randomly freezes for a few seconds and then resumes. This happens most often when opening large files or running multiple applications. Event Viewer shows no critical errors. Which component is most likely causing the issue?

Accepted Answer

Failing hard drive or SSD. Intermittent freezing under load without errors often points to a failing storage drive. Hard drives with bad sectors or a failing controller can cause the system to pause while retrying reads or writes. SSDs can also cause stuttering if their controller is failing or if TRIM is not functioning.

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Insufficient RAM

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Overheating CPU

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Outdated network driver

Question 15

A technician upgrades a PC from a traditional HDD to an NVMe SSD. After installation, the BIOS detects the SSD, but Windows does not appear in the boot menu. What should the technician do to resolve this?

Accepted Answer

Set the BIOS to UEFI boot mode and ensure the SSD is GPT partitioned. When migrating from an HDD to an NVMe SSD, the BIOS may detect the drive but the boot configuration may be missing or incorrect. The solution is to ensure the boot mode is set to UEFI (not Legacy) and that the drive is formatted with GPT, as NVMe drives require UEFI to boot.

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Change the SATA mode from AHCI to IDE

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Enable Legacy boot mode in BIOS

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Update the chipset drivers

Question 16

During a deployment, you install a new graphics card into a desktop PC. After powering on, the system boots but the display is blank. The monitor is known to work, and the card's fans spin. What should you check next?

Accepted Answer

Check that the monitor cable is connected to the graphics card, not the motherboard. Fans spinning indicates the card is receiving power, but a blank display often means the monitor is not receiving a signal. The most common oversight is connecting the display cable to the motherboard's video port instead of the new graphics card's ports.

Answer

Replace the graphics card

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Update the BIOS

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Reseat the RAM

Question 17

A technician is troubleshooting a desktop that will not boot. The power LED is on, fans spin, but there is no display and no beep codes. The CPU and RAM have been reseated, and the motherboard appears to have power. What should the technician check next?

Accepted Answer

Inspect the CPU socket for bent pins. With power, fans, and no beep codes, the system is likely not completing POST. The most common cause after reseating CPU and RAM is a bent CPU socket pin or a misaligned CPU, which can prevent the system from initializing the processor. This is a common issue on LGA sockets.

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Test the power supply with a multimeter

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Replace the CMOS battery

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Flash the BIOS

Question 18

A customer complains that their PC randomly shuts down after about 30 minutes of use, especially when playing games. The case feels warm to the touch. What should you check first?

Accepted Answer

Check CPU and GPU temperatures. Random shutdowns under load are classic symptoms of overheating. The warm case reinforces this, so checking CPU and GPU temperatures should be the first step to confirm thermal throttling or thermal protection.

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Replace the power supply

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Update the graphics driver

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Run a memory diagnostic

Question 19

A user reports that their PC powers on for a second then immediately shuts off. This repeats in a loop. What is the most likely hardware issue?

Accepted Answer

Incorrectly installed motherboard standoffs causing a short. The power-on-then-off loop is a classic symptom of a short circuit or power issue, often caused by a loose standoff, improperly seated component, or a failing power supply. The most common cause is a short to ground from a motherboard standoff in the wrong location.

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Defective CPU

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Overheated GPU

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Corrupted BIOS

Question 20

A user reports that their desktop PC emits a series of short beeps and fails to boot. The monitor shows no display, and the keyboard and mouse LEDs are off. What is the most likely cause?

Accepted Answer

Loose or faulty RAM module. A series of short beeps during POST typically indicates a memory (RAM) failure. The lack of display and peripheral response points to a hardware fault that prevents the system from completing POST, and RAM is the most common culprit.

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Faulty power supply unit

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Defective hard drive

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Overheated CPU