It powers on but there is no display
Fans spin and lights come on, but the screen stays black. The checks, in order of likelihood.
Safety level: safe diy · Time: about 20 minutes · Level: beginner
Fans spin, lights come on, and the monitor says no signal. The machine is running — something between it and the screen is not.
Applies to
Desktop PCs. The great majority of these are one of the first four checks.
Steps
- Check the monitor itself. Is it on? Is it on the right input? A monitor with three inputs defaults to the wrong one constantly. Cycle through them. Test the monitor on something else — a laptop, a console — to rule it out entirely.
- Check which socket the cable is in. This is the most common cause by a distance. If the machine has a graphics card, the display cable must go into the card, low down at the back — not into the ports on the motherboard higher up. A cable in the board's port on a machine with a graphics card produces exactly this symptom.
- Reseat the cable at both ends, and try a different cable. HDMI and DisplayPort cables fail more often than people expect.
- Listen and look for what it is doing. Does it reach the same point every time? Do the fans spin up and settle, or spin at full speed and stay there? Full speed with no display often means the board is not completing its startup checks.
- Check for diagnostic indicators. Many boards have four small labelled LEDs (CPU, DRAM, VGA, BOOT) and stop at the one that failed. Some have a two-digit code display. Either tells you the answer immediately — look it up in the board manual.
- Reseat the memory. Power off, unplug, hold the power button five seconds, discharge yourself on bare metal, then press each stick down until the clips close by themselves. Unseated memory is a very common cause of no display, especially after the machine has been moved.
- Try one stick alone, in the slot the manual specifies for single-stick operation.
- Reseat the graphics card. Release the retention clip on the slot, remove, refit until it clicks. Check its power cables are firmly connected.
- Test with the motherboard's own display output if the processor supports it: remove the graphics card entirely and connect to the board. Getting a picture this way points squarely at the card.
Expected result
Either a display, or a specific piece of information — a diagnostic LED, a code, or "it works without the graphics card" — that narrows it to one component.
If it does not work
If there is still nothing after all of the above, the fault is likely the graphics card, the memory, the board or the processor, and separating them needs known-good spares to swap in.
Stop and ask a technician if
- You smell burning or see scorching
- The machine powers off by itself partway through
- It worked before a storm or a power cut
- You have been through the above twice
When you bring it in, tell us what the diagnostic LEDs showed and whether it worked without the graphics card. Those two facts often save an hour.
Read this next
- The PC is completely dead: no lights, no fans — If nothing lights up at all, start there instead — this guide assumes it powers on.
- New memory is not detected, or the PC will not boot after fitting it — Memory that is not fully seated is one of the commonest causes of no picture.
- Track a repair or service job — If none of these bring a picture back, book it in rather than keep trying.
Still stuck?
If anything here does not match what you are seeing, stop rather than force it. Contact us · Book a repair
Last reviewed 2026-08-19.