OnSiteTech | Desktop Computer Troubleshooting
You press your computer’s power button.
The fans start spinning, the case lights
come on, but your monitor stays black
or displays a No Signal message.
If your computer turns on but
shows no display, the problem may
involve the monitor connection,
graphics card, memory, or the
computer’s startup hardware checks.
The good news is that a blank screen
does not automatically mean your
graphics card or motherboard is dead.
Some causes can be identified using
simple external checks.
This guide explains the different
symptoms, what they may indicate,
which troubleshooting steps are safe
to try, and when professional
diagnosis becomes appropriate.
Why Does My Computer Turn On
but Show No Display?
Quick Answer
If your PC turns on but shows no image,
start by checking whether the monitor
has power, the correct HDMI or
DisplayPort input is selected, and
the video cable is connected
to the appropriate computer output.
Try a different compatible cable
or monitor when available.
If no image appears before Windows
starts, the issue may involve
graphics output, memory initialization,
or another hardware startup problem.
If the manufacturer logo appears
before the screen goes black,
the problem may instead involve
Windows, display settings,
or the graphics driver.
The first step is identifying
when the image disappears.
A PC that never displays BIOS
requires different troubleshooting
from one that starts Windows
and then loses its picture.
Important Safety Warning
Stop troubleshooting if you notice
smoke, sparks, burning smells,
liquid damage, damaged power cables,
or unusual electrical noises.
Disconnect external power when safe.
Never open a power supply unit,
touch exposed electrical contacts,
or attempt live electrical testing.
What Happens When Your PC Starts?
Choose the description that matches
your situation. These suggestions
help identify the next safe check
but do not confirm which component
has failed.
PC fans spin, but the monitor
shows No Signal
The monitor is not detecting
a usable video signal on its
selected input.
Start with the monitor input,
HDMI or DisplayPort cable,
and the computer’s video output.
Computer powers on, but BIOS
never appears
The system may not be completing
its hardware initialization,
although a faulty display connection
can produce similar symptoms.
The Windows logo appears,
then the screen turns black
This may involve graphics drivers,
display settings, startup software,
or other operating-system issues.
No display after installing RAM
The issue may relate to memory
installation, compatibility,
or startup configuration.
No display after installing a GPU
The video cable may be connected
to the wrong output, or the
graphics card may need
installation or power checks.
Computer displays an image sometimes
but not always
Intermittent video loss may involve
cables, display connections,
graphics hardware, or
other unstable components.
No Power, No Video, No POST or No Boot?
These terms describe different
computer startup failures.
Understanding the difference
helps avoid unnecessary
part replacement.
| Condition | Typical Symptoms | First Area to Check |
|---|---|---|
| No Power | No lights, fans or normal response to the power button |
Power outlet, external cable, power supply and power connections |
| No Video | Computer appears active, but the monitor displays nothing or shows No Signal |
Monitor, cable, video output and graphics hardware |
| No POST | The PC receives power but does not complete its initial hardware startup checks |
Diagnostic indicators, memory and hardware initialization |
| No Boot | The startup logo appears, but the operating system does not load correctly |
Windows startup, storage, boot configuration and recovery |
For example, a computer displaying
the manufacturer’s logo is not
experiencing the same failure
as a machine that never
produces a startup image.
Also, spinning fans do not prove
that the CPU, memory, graphics card
or motherboard are working correctly.
7 Checks to Try When Your Computer
Turns On but Has No Display
Start with simple external checks.
Do not open the computer unless
you understand the manufacturer’s
safety instructions and are
comfortable working with
computer components.
STEP 01
Check Whether the Monitor Is Working
A computer can be running normally
while its monitor is switched off,
connected incorrectly, or set
to the wrong input.
What to do
- Confirm that the monitor’s
power indicator responds. - Check its power cable
and wall connection. - Open the monitor’s own
on-screen menu, if available. - Select the correct HDMI
or DisplayPort input. - Test the monitor with another
known-working device if possible.
If the monitor cannot display
its own menu or an image from
another known-working device,
the monitor itself may need
further investigation.
STEP 02
Inspect HDMI and DisplayPort Connections
A loose or damaged video cable
can prevent a usable signal
from reaching the display.
What to do
- Turn off the PC and monitor.
- Check both ends of the video cable.
- Reconnect the cable firmly
without forcing the connector. - Inspect for visible
connector or cable damage. - Try another known-working
compatible cable if available.
A damaged cable can sometimes
cause intermittent picture loss
rather than a completely
blank screen.
STEP 03
Make Sure the Monitor Is Connected
to the Correct Graphics Output
Many desktop computers have
video connectors on the motherboard
and separate connectors on
a dedicated graphics card.
If your computer uses a dedicated
GPU, the monitor is generally
connected directly to
that graphics card.
What to do
- Look at the back of the computer.
- Identify the motherboard
video outputs. - Locate any separate video
ports on the dedicated GPU. - Confirm that your monitor is
connected to the intended output. - Restart the computer
and check for an image.
Important:
A motherboard video connector
will not necessarily work
when your processor lacks
integrated graphics.
Do not assume that every HDMI
port on a computer is active.
STEP 04
Disconnect Unnecessary External Devices
USB accessories, external storage
or docking equipment can complicate
startup troubleshooting.
What to do
- Shut down the computer normally
if possible. - Disconnect non-essential
USB accessories. - Remove external drives
and unnecessary peripherals. - Leave the monitor connected.
- Try starting the computer again.
If a normal image returns,
reconnect accessories individually
to see whether the problem
is associated with one device.
STEP 05
Try Another Known-Working Display
Using a second monitor or
compatible television can help
separate a display problem
from a computer startup issue.
What to do
- Turn off both devices.
- Connect the PC to another
known-working display. - Select the appropriate
input on that display. - Start the PC and look for
the manufacturer’s logo. - Note whether the result
differs from the original monitor.
If the second display works,
investigate the original monitor,
its cable and connection.
If neither display works,
further checks may be required.
This result alone does not
prove a graphics card failure.
STEP 06
Check Motherboard Diagnostic Lights
and Beep Codes
Some desktop motherboards
provide diagnostic indicators
for startup hardware problems.
Common indicator labels include
CPU, DRAM, VGA and BOOT.
However, their meaning varies
by manufacturer and motherboard model.
What to do
- Find the exact motherboard
or desktop model. - Observe any diagnostic lights
without touching internal components. - Record the light labels,
colours or repeating patterns. - Listen for repeating beep codes
if the system includes a speaker. - Compare the indicators with
the official model documentation.
Helpful diagnostic clue:
A DRAM warning may indicate
a memory-initialization problem,
while a VGA warning may point
toward graphics initialization.
Neither warning automatically
proves that a specific part is dead.
STEP 07
Determine Whether the Problem Happens
Before or After Windows Starts
A black screen after Windows starts
is different from a PC that
never displays BIOS.
What to check
- Does the manufacturer’s logo appear?
- Do you see a Windows loading screen?
- Does the display turn black
only after the login screen? - Does the computer respond
to keyboard input? - Did the problem begin after
a graphics-driver or Windows update?
If Windows is running,
pressing
Windows + Ctrl + Shift + B
may restart the Windows graphics driver.
Important distinction:
This shortcut cannot fix a computer
that has failed its hardware startup
checks or never loaded Windows.
Hardware Problems That Can Cause No Display
When external checks do not
restore the image, possible
hardware causes include
RAM initialization issues,
graphics-card problems,
motherboard faults or
other startup failures.
A black screen alone is not
enough to identify the
faulty component.
Can Bad RAM Cause a Computer
to Turn On Without Display?
Yes. Faulty, incompatible or
incorrectly installed RAM can
prevent some computers from
completing POST.
This may happen after installing
new memory, moving the computer,
or changing BIOS memory settings.
A professional diagnosis may involve
checking motherboard compatibility,
supported memory configurations,
individual modules and
diagnostic error indicators.
Before opening the case:
Shut down and disconnect external
power. Follow the computer
manufacturer’s safety instructions.
If you are unfamiliar with
electrostatic discharge precautions
or internal components,
request qualified assistance.
Can a Graphics Card Cause
a Black Screen?
A graphics card can cause
a missing display signal
if it is malfunctioning,
incorrectly connected,
or unable to initialize.
However, incorrect monitor input,
a damaged video cable,
or an inactive output can
produce similar symptoms.
For a custom-built PC,
document the graphics card model,
any recent hardware changes,
and whether motherboard diagnostic
lights remain illuminated.
What If the Computer Turns On
but Never Shows BIOS?
If there is no BIOS image,
the computer may be unable
to complete its initial hardware
checks, or the video signal
may not be reaching the monitor.
The distinction matters because
reinstalling Windows will not
solve a PC that cannot
complete hardware initialization.
Should You Clear CMOS or Reset BIOS?
Resetting firmware settings can
sometimes help after an incorrect
configuration, but it should
not be a first troubleshooting step.
A CMOS reset can change memory,
storage, boot and security-related
settings. Procedures vary by motherboard.
Follow the official manufacturer
instructions or request technical
assistance rather than removing
components at random.
Computer Shows the Startup Logo,
Then the Screen Goes Black
If you can see the manufacturer’s
logo or BIOS interface before
the display disappears,
the issue may occur later
during Windows startup.
Potential causes include graphics-driver
problems, display configuration,
Windows startup errors
or other software and hardware issues.
What Should You Check?
- Record the exact moment
the picture disappears. - Check whether Windows reaches
its sign-in screen. - Disconnect unnecessary
external displays. - Note any recent driver
or Windows updates. - If appropriate, follow Microsoft’s
official blank-screen recovery guidance.
Before attempting Windows recovery,
system resets or reinstallation,
make sure important files are
protected and that you understand
the potential effect on stored data.
If the PC is unable to display
anything before BIOS,
focus on startup and video
diagnostics instead.
Computer No-Display Symptoms:
Possible Causes and Next Steps
| Symptom | Possible Area to Investigate | Safe Next Step |
|---|---|---|
| Monitor displays No Signal | Input selection, cable or video output |
Check monitor and cable connections |
| Fans spin but no BIOS appears | Display output or hardware initialization |
Test another display and record diagnostic lights |
| No display after RAM installation | Memory compatibility or initialization |
Check official compatibility and installation instructions |
| No display after GPU installation | Graphics output, connection or power |
Review supported outputs and installation guidance |
| Windows logo appears, then black screen |
Windows startup or graphics drivers |
Follow Windows blank-screen troubleshooting |
| Display works intermittently | Connections, graphics hardware or unstable components |
Record when the failure occurs and arrange diagnosis if recurring |
These are diagnostic starting points,
not confirmed fault diagnoses.
Several hardware and software problems
can produce the same visible symptom.
When Should You Request Professional
Computer Repair?
Consider professional diagnosis
when the computer still shows
no image after known-working
monitor and cable checks.
Further investigation is particularly
important when:
- The PC never displays BIOS.
- A motherboard diagnostic light
remains illuminated. - The screen stopped working
after a hardware upgrade. - The PC repeatedly starts
and shuts down. - You are not comfortable
working inside the computer. - Important files may be at risk
from further troubleshooting.
Is It Better to Repair or Replace the PC?
That depends on the actual fault,
the computer’s age,
replacement-part availability,
repair cost and your performance needs.
A monitor cable problem is very
different from a failed motherboard.
It is usually better to understand
the fault before replacing
expensive components.
Calgary & Surrounding Communities
On-Site Computer Troubleshooting
Service Areas
If your computer powers on
but shows no display,
OnSiteTech provides on-site
computer support in
Calgary.
Requests from surrounding communities
can also be assessed for
appointment availability
and applicable travel arrangements.
Calgary
Airdrie
Chestermere
Cochrane
Okotoks
Strathmore
Crossfield
High River
Diamond Valley
Canmore
Banff
Listing a community does not guarantee
a specific appointment or repair
availability. Travel charges and
service suitability depend on
your requested location.
Explore Helpful OnSiteTech Resources
PRIMARY SERVICE
Computer Repair
Explore repair and troubleshooting
options for desktop startup,
display and hardware problems.
RELATED SERVICE
Laptop Repair
Laptop blank-screen problems
may require a different
diagnostic approach from
desktop computer faults.
PRICING
On-Site Repair Pricing
Review published labour rates,
travel arrangements and
service terms before booking.
REPAIR PROCESS
How On-Site Repair Works
Learn what happens after submitting
a request and what to expect
during an on-site assessment.
Frequently Asked Questions
Why is my PC turning on
but not displaying anything?
Check the monitor’s power,
selected input, cable
and computer video output.
If these work but no startup
image appears, hardware
initialization or graphics
problems may need diagnosis.
Why do my PC fans spin
but there is no display?
Spinning fans indicate that
some power is reaching the computer.
They do not prove that the PC
completed its startup hardware
checks. Check the monitor,
connections and any diagnostic
indicators.
What does No Signal mean
on a computer monitor?
It generally means the monitor
is not receiving a usable video
signal on the selected input.
Check the input source, cable
and computer output.
Can bad RAM cause no display?
Yes. Faulty, incompatible
or improperly installed memory
can prevent some computers
from completing POST.
A black screen alone does
not confirm RAM failure.
Can a faulty graphics card
cause a black screen?
Yes. Graphics hardware problems
can prevent a usable video output.
However, monitors, cables
and incorrect output selection
can create similar symptoms.
Does no BIOS screen mean
the motherboard is dead?
No. Missing BIOS video may involve
display connections, memory,
graphics initialization or
other startup hardware problems.
Further diagnosis is required.
What are the signs of a dead CPU?
A completely failed processor
may prevent startup, but a
blank screen is not enough
to diagnose CPU failure.
Motherboard, firmware,
memory and power problems
may produce similar symptoms.
Why did my computer stop displaying
an image after changing RAM?
The problem may involve memory
compatibility, installation
or firmware settings.
Consult the motherboard’s
official guidance before
changing internal components.
Can I use Windows + Ctrl + Shift + B
when BIOS does not appear?
No. The shortcut can restart
the Windows graphics driver
when Windows is running.
It cannot fix a computer
that has not passed POST
or loaded the operating system.
Is the black screen of death fixable?
Many blank-screen problems
can be resolved, but the
appropriate repair depends
on whether the issue involves
Windows, the display, graphics
hardware or startup components.
Should I remove the CMOS battery
to fix no display?
Not as an initial step.
A firmware reset may alter
important configuration settings.
Use the exact manufacturer’s
procedure or consult
a qualified technician.
Can OnSiteTech diagnose a desktop
PC at my home in Calgary?
OnSiteTech provides on-site
computer support in Calgary
and considers requests from
eligible surrounding communities.
Some complex repairs may need
parts or additional arrangements.
Official References and Safety Guidance
This educational guide uses general
computer troubleshooting principles
and manufacturer support guidance.
The exact diagnostic procedure
depends on the computer model
and installed components.
Do not open a power supply,
handle live electrical components,
or attempt repairs beyond
your training and experience.
OnSiteTech | Calgary & Area
Computer Turns On but the Screen
Is Still Black?
You do not need to know whether
the RAM, graphics card or
motherboard is responsible
before requesting assistance.
Describe what happens when
your computer starts,
and OnSiteTech can assess
whether an on-site visit
is appropriate.
- Tell us whether the monitor
is black or says No Signal. - Share your PC make, model
or custom-build specifications. - Mention any recent RAM,
GPU or other hardware changes. - Describe diagnostic lights,
beeps or unusual sounds. - Let us know if important
files need protection. - Include your location
when submitting the request.
Published on-site labour rates
and service terms apply.
Diagnosis does not guarantee
completion of every repair
during a single visit.
Appointment availability
and travel arrangements
depend on the requested location.
This article provides general
educational troubleshooting information.
Stop using equipment showing signs
of electrical damage or overheating.
Protect important data before
invasive hardware repairs
or system recovery.