Monitor Says “No Signal”: Desktop Display Won’t Come On

"No signal" means the monitor is powered and awake, and is receiving nothing on the input it is currently watching. The computer may be perfectly fine.

Step 1 — Check the input source

Press the monitor's own menu button and confirm the selected input matches the cable actually plugged in. A monitor on DisplayPort while the cable is in HDMI shows exactly this message, and nothing else you do will help.

Step 2 — Check which output you are plugged into

On a desktop with a graphics card, the motherboard's video ports are usually dead once a card is fitted. Move the cable to the graphics card's ports — lower down on the back of the case.

This single mistake accounts for a large share of "no signal" after someone has moved or cleaned the machine.

Step 3 — Swap the cable and the port

1. Try a different cable of a different type where possible.
2. Try another output on the graphics card.
3. Try the monitor on another computer, or a laptop.

If the monitor works on a laptop, the monitor and cable are fine and the fault is inside the desktop.

Step 4 — Wake the machine and force output

1. Press a key, move the mouse, then press the power button once and wait.
2. Win+P → Duplicate if there is any sign of Windows running.
3. A hard reset: hold power for ten seconds, unplug for thirty, then power on. GPU state can survive a soft restart.

Step 5 — If the desktop never POSTs

1. Check for beeps and for a lit diagnostic LED on the board.
2. Reseat the graphics card — fully, until the slot latch clicks — and check the PCIe power cables click home. A card that is powered but not seated gives no signal and no error.
3. Reseat the memory, one stick at a time in the slot nearest the CPU.
4. Clear CMOS.
5. Try the integrated graphics — remove the card entirely and use the motherboard output. If that displays, the card or its power is the fault.

Step 6 — Resolution and refresh rate

A monitor that only supports 1080p60 connected to a machine forcing 4K120 will show "out of range" or nothing. Boot into Safe Mode (which loads a basic display driver) — if you get a picture there, the resolution or refresh rate is the problem, and you can correct it before returning to normal boot.

The monitor is fine, the cable is fine, still nothing

Then the panel is not the story: the machine is not producing an image. Treat it as a POST failure — power supply, memory, graphics card — and work through the "computer won't turn on" guide from the point where fans spin but nothing appears.

One more thing worth checking: a monitor with a failing backlight can show "no signal" over a nearly invisible dim image. Shine a torch at it. If you see a picture, the message was a red herring and you need the backlight guide.