Monitor No Signal but PC Is On? Fix Input, Cable and GPU Port

“No signal” is the monitor telling you two useful things: it has power and its electronics work, but nothing is arriving on the input it’s listening to. So the cause is almost always the input setting, the cable or port, or a computer that isn’t sending video, not a dead monitor.

The fastest way to narrow it down: check whether the computer is actually running. Look for fans, a power light, and a keyboard light that toggles when you press Caps Lock. If it is running, the problem is the input, cable, port or a Windows display setting. If the computer shows signs of life but never shows a picture on any screen, it isn’t finishing startup, which is covered further down.

What the monitor is telling you

Start by unplugging the video cable with the monitor switched on. Most monitors then show a no-signal or self-test message; Dell calls this the self-test feature check. If that message appears, the monitor itself works. If the screen stays completely black with no message and no menu, the monitor or its power is the problem.

Input source and cable order

Most office monitors have two or three inputs, and many don’t switch automatically. Press the monitor’s input or source button (sometimes inside the on-screen menu) and choose the exact port. HDMI 1 and HDMI 2 count as different inputs.

Then work through the cable in this order, testing after each step:

1. Turn the monitor off, unplug its power cord for a few minutes, then plug it back in and turn it on.
2. Reseat both ends firmly. Full-size DisplayPort plugs usually lock: press the release button on the plug before pulling it out, and push it back in until it clicks.
3. Try a known-good cable of the same type.
4. Try a different input on the monitor.
5. Try a different video port on the computer.
6. Remove anything in between, such as a KVM switch, splitter, adapter, extension or dock, and connect the monitor directly.

Adapters deserve suspicion. If the monitor works over a direct cable but not through an adapter, replace the adapter. Adapter direction matters too, as does whether a USB-C port carries video at all; the connection table in our second monitor guide covers both.

Desktop PCs: graphics card or motherboard port?

This catches a lot of people after an office move, a cleaning or a new monitor. Many desktops have two sets of video ports: motherboard ports near the top of the back panel, and graphics card ports lower down in a horizontal slot. Dell’s guidance is simple: if the computer has a dedicated graphics card, use its ports. It’s also the usual reason for a monitor no signal after installing graphics card upgrades: many desktops turn off the motherboard ports once a card is fitted, so move the cable to the card.

There are two common reasons the motherboard ports stay dark:

• Many computers switch off the motherboard’s video output when a graphics card is installed.
• Some processors have no built-in graphics at all. Intel marks desktop chips that require a separate graphics card with an F at the end of the model number, such as a Core i5 ending in F. Many AMD Ryzen desktop chips, such as the Ryzen 5 5600X, have none either; AMD’s spec pages list them as “Discrete Graphics Card Required.” On those computers the motherboard ports never work.

If you just installed or reseated a graphics card, power off, unplug, touch bare metal on the case to discharge static, and check that the card is fully seated in its slot and that its power cables from the power supply are connected. Many cards won’t output video without them.

The PC is on but Windows isn’t sending a picture

If you see the manufacturer logo and then lose the picture as Windows starts, Windows is sending a mode the monitor can’t show, the display is set to the wrong screen, or the driver has crashed.

• Try Windows + Ctrl + Shift + B, the shortcut that restarts the graphics driver; you should hear a beep or see a flash.
• Press Windows + P, press P again and then Enter to move to the next display mode. Repeat a few times, pausing between tries.
• On a laptop with an external monitor, open the lid so you can see the built-in screen. If Windows is set to PC screen only, the external monitor gets no signal; press Windows + P and choose Duplicate or Extend.
• If a resolution change caused it, wait without pressing anything; Windows reverts a display change you don’t confirm.
• Still black: start Safe Mode and roll back or reinstall the display driver. Microsoft’s method is to hold the power button for 10 seconds to force the computer off during startup, and repeat two or three times until it opens the recovery environment. Then go to Troubleshoot > Advanced options > Startup Settings > Restart and press F5 for Safe Mode with Networking.
• If the picture disappeared after a resolution or refresh-rate change that a restart didn’t undo, use the same Startup Settings screen but press 3 or F3 for Enable low-resolution video, which starts Windows with your current driver at a low resolution and refresh rate. Then pick a supported mode under Settings > System > Display; the refresh rate is under Advanced display.

Forcing a computer off is a last resort because unsaved work is lost. If the drive is encrypted, Windows may ask for the BitLocker recovery key in the recovery environment; our guide to finding a BitLocker recovery key shows where it’s stored.

The PC isn’t finishing startup

If no monitor shows anything, not even the manufacturer logo, the computer is failing before Windows. The monitor is reporting accurately: the computer never got far enough to send a picture.

• Look and listen before opening anything. Many desktops beep or flash a power or status light in a pattern that identifies the failed part; look it up in the computer or motherboard manual.
• Do a hard reset: shut down, unplug the power cord, disconnect everything except the keyboard, mouse and monitor, hold the power button for 15 to 20 seconds to drain leftover power, then plug it back in and turn it on.
• Undo recent hardware changes, such as new memory, a new graphics card or a new drive. Before opening the case, unplug the power cord, touch bare metal on the case to discharge static, and hold parts by their edges.
• Reseat the memory modules, pressing each one in until its clips lock.
• On Dell desktops, run the power supply self-test Dell documents. On models with a test button on the power supply, a steady light and a spinning power-supply fan mean it passed.
• If the processor has built-in graphics, remove the graphics card and try a motherboard port to see whether the card has failed.

Laptops behave differently, because the screen and power system are built in. For a laptop that shows nothing, use our laptop won’t turn on guide, or the brand guides for Dell laptops that won’t turn on and HP laptops that won’t turn on.

Monitors that show no signal after sleep

If a monitor works all day but shows “No signal” every morning or after lunch, first work out whether the computer woke up at all.

• Press Caps Lock. If its light doesn’t respond and the fans are quiet, the computer is probably still asleep: press its power button briefly to wake it. Don’t hold the button, which forces it off.
• If the power button wakes it but the keyboard never does, the keyboard isn’t allowed to wake the computer. In Device Manager, expand Keyboards, open the keyboard’s Properties and, on the Power Management tab, tick Allow this device to wake the computer. This needs an administrator account, and some keyboards don’t offer the option.
• If the computer is awake but the monitor stays on “No signal”, press Windows + P and choose Extend or Duplicate. Dell lists this as known behavior for some USB-C dongles, which don’t wake the monitor until a display mode is chosen.
• If the monitor itself seems stuck, unplug its power cord for a few minutes, and check its menu for power-saving or automatic input options that affect wake-up.
• Through a dock, update the dock firmware and graphics driver. The full dock checklist, and what to do if Windows doesn’t list the monitor once it’s awake, is in the second monitor guide linked above.
• Update the BIOS only if the computer maker’s release notes list a display or wake fix. Keep a laptop on AC power and don’t interrupt the update, because a failed BIOS update can leave the computer unable to start. On a BitLocker-encrypted computer, suspend BitLocker first so it stays suspended through every restart of the update (our BitLocker recovery key guide gives the command; the Control Panel option resumes after one restart and isn’t on Windows 11 Home), and have the recovery key ready; check afterward that protection is back on.
• If several desks share the same dock and monitor model, fix it on one desk, confirm it holds for a few days, then roll the same updates out to the rest.

Conference-room TVs and projectors

A TV or projector that says “No signal” follows the same logic, with a few differences worth knowing for a meeting room:

• Use the TV’s remote, not the computer, to pick the input. TVs often have three or four HDMI inputs, and the label next to the port you used is the one to select.
• Press Windows + P and choose Duplicate so the room sees what’s on the laptop. If the TV still shows nothing, try Second screen only briefly, then switch back.
• Long HDMI runs through walls and floor boxes are a common weak point. Test with a short cable straight from the laptop to the TV to rule out the building’s cabling.
• For a wireless display adapter plugged into the TV, press Windows + K on the laptop to open Cast and select the adapter.
• Test any USB-C to HDMI adapter kept in the room with a laptop you know outputs video over USB-C, because not every USB-C port does.

Label the room’s cable and adapter with the input they belong to, so the next person picks the right one first time.

When to stop and get help

• The monitor shows no self-test message and no menu with nothing connected: it needs repair or replacement.
• The computer never shows a logo on any monitor after you’ve reseated memory and removed new parts.
• A burning smell, smoke, or a buzzing or clicking power supply: unplug the computer and leave it off until it has been checked.
• A graphics card that gives no picture from any of its ports, even though the computer works from the motherboard port with the card removed. Fans that don’t spin aren’t a fault on their own, because many cards stop their fans while they’re cool.
• Bent pins in a VGA or DVI connector, or a cracked HDMI or DisplayPort socket.

Most no-signal problems need someone at the desk to check inputs, cables and ports, so we can’t promise a remote fix. Once a picture is back, driver and display-setting problems can often be handled through our remote computer help service, in a session you approve and can end at any time. For failed hardware, a local computer repair shop or the manufacturer’s warranty service is the better route.

Common questions

Why does my monitor say no signal when the computer is on?

The monitor isn’t receiving video on the input it’s set to. Check the input source button first, then the cable at both ends. On a desktop with a separate graphics card, make sure the cable is in the card, not the motherboard. If the computer is asleep, wake it with the keyboard. If no monitor shows even the startup logo, the computer isn’t finishing startup.

How do I change the input on my monitor?

Most monitors have a button labeled Input or Source, or an input option in the on-screen menu, opened with the menu button or a small joystick on the back or underneath. Choose the exact port your cable uses; HDMI 1 and HDMI 2 are separate inputs. If the monitor has an automatic input option, turning it on lets it find the active input itself.

Can a bad HDMI cable cause no signal?

Yes. A damaged or worn cable can carry no picture at all, or drop out at higher resolutions. Older cables may not handle 4K at 60Hz and show no signal or flicker instead. Swap in a known-good cable before changing anything else, and leave out extensions, couplers and switches while you test.

Why does my monitor say no signal on DisplayPort when HDMI works?

Check that the DisplayPort plug is fully latched and the monitor’s input is set to DisplayPort, not HDMI. Unplug the monitor’s power for a few minutes, then try another DisplayPort cable. A passive DisplayPort-to-HDMI adapter only works from a DisplayPort output to an HDMI screen, never the reverse. Some monitors also have a DisplayPort version or daisy-chain (MST) setting in their menu; if DisplayPort stopped working after it was changed, set it back using the user guide.

Why does my monitor go to no signal after sleep?

Either the computer didn’t actually wake, or it woke but the monitor didn’t get a fresh signal. If the Caps Lock light doesn’t respond, press the power button briefly; if that works, allow the keyboard to wake the computer in Device Manager. If the computer is awake, press Windows + P and choose Extend or Duplicate. With a dock, update its firmware and the graphics driver, and the BIOS only if its release notes list a display or wake fix, after suspending BitLocker.

Can bad RAM cause no signal on a monitor?

Yes. If a memory module is loose or has failed, the computer can’t finish its startup self-test, so it never sends a picture and the monitor reports no signal. Fans and lights come on, but no logo appears, and many desktops beep or flash a light pattern for memory errors. Unplug the computer, touch bare metal on the case, reseat each module until its clips lock, and if that fails, test with one module at a time.

Is my monitor broken if it says no signal?

Usually not. The no-signal message itself shows that the monitor’s power and electronics work. To confirm, unplug the cable with the monitor on: if it shows a no-signal or self-test message, it’s fine. If the screen stays black with no message or menu even though the power light is on, or it still shows no signal on another computer with a known-good cable and the right input selected, it most likely needs repair or replacement.