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ProblemDesktop PC

PC turns on but no display

The PC shows signs of power, but the monitor has no usable picture. Check the monitor, selected input, cable and video output before moving on to internal components.

Try this first

3 quick checks · ~7 min

  1. Check monitor power and inputStart outside the PC.
  2. Check the display cableBoth ends should be securely connected.
  3. Use the correct video outputMotherboard and graphics-card outputs are not equivalent in every PC.

Find your situation

See all the clues. Choose the one that matches what you observe.

The monitor reports “No Signal”

Check its selected input and the video cable connection.

A signal is present, but the screen stays black

Start with the display and cable checks. A black picture alone does not identify a failed part.

BIOS appears; the picture disappears in Windows

Video works during the initial boot. Treat this differently from a PC that never produces a picture.

The DRAM debug LED stays on

This points toward memory detection or installation, not proof of a broken RAM module.

The VGA debug LED stays on

Inspect graphics connections before concluding that the graphics card has failed.

Diagnostic signals

ObservationDRAM LEDInspect the memory path
Check your motherboard manual for the LED meaning. A persistent indicator helps choose the next inspection.
ObservationVGA LEDInspect the graphics path
The indicator narrows the area to investigate; it does not establish that the card is defective.

Step-by-step solutions

01

Check monitor power and input

  • Estimated time: 2 min
  • Easy

Start outside the PC.

  1. Make sure the monitor has power and is switched on.

  2. Use its input menu to select the connector you are using, such as HDMI or DisplayPort.

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02

Check the display cable

  • Estimated time: 3 min
  • Easy

Both ends should be securely connected.

  1. Reconnect the cable at the monitor and PC. Try another compatible cable or port if one is available.

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03

Use the correct video output

  • Estimated time: 2 min
  • Easy

Motherboard and graphics-card outputs are not equivalent in every PC.

  1. If you use a dedicated graphics card, check that the monitor is connected to it. A motherboard output requires a processor and configuration that support integrated graphics.

Sources:
04

Identify when the picture is lost

  • Estimated time: 5 min
  • Easy

Record visible clues before changing parts.

  1. Disconnect nonessential external peripherals and check any motherboard debug LEDs.

  2. If BIOS is visible but the screen goes black when Windows starts, note that transition and seek Windows startup support before dismantling the PC.

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Advanced

Advanced checks

Continue if the earlier steps did not help. Read each procedure’s precautions first.

05

Check how the RAM is installed

  • Estimated time: 15 min
  • Intermediate
  • Moderate risk
  • Restart required

Continue here only after the external checks.

  1. Reseat memory as directed by the motherboard manual. If several modules are fitted, test one at a time in the manufacturer-recommended slot.

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06

Check the graphics-card connection

  • Estimated time: 15 min
  • Intermediate
  • Moderate risk
  • Restart required

For systems with a dedicated GPU.

  1. With power disconnected, check the card installation and required power connectors. Reseat the card if appropriate, following its installation guide.

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07

Test a minimal POST configuration

  • Estimated time: 25 min
  • Advanced
  • Moderate risk
  • Restart required

You need to be able to identify the system connections.

  1. Follow the board guide: CPU with cooling, one RAM module, power and a monitor. Keep a graphics card if it is needed for video output.

  2. If video returns, shut down and unplug the PC before reconnecting each device individually to narrow the cause.

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08

Consider clearing CMOS last

  • Estimated time: 20 min
  • Advanced
  • High risk
  • Restart required

This can reset BIOS or firmware settings.

  1. Use the exact procedure for your motherboard, with external power disconnected. Do not guess jumper positions or treat BIOS flashing as a generic fix.

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Next step

Still not working?

Contact the manufacturer or a repair technician with the motherboard, CPU and GPU models and the observed debug LEDs. If BIOS is visible, explain that the display disappears only when Windows starts.

Sources

Documentation behind this guide. Editorial recommendations are identified separately.

Source review: . A documentation review, not a physical hardware test.