The monitor writes No signal, No signal detected, Check the signal cable, What does this mean and what should i do?

A common question from users is what to do if the monitor writes “No signal” but the computer works, as well as what the following messages mean: No signal detected, Check signal cable, No entry sign, “Check cabin”, “No signal detected “and the like. The problem can occur with any type of connection: HDMI, VGA, Display Port y DVI.

This manual details why there is no signal or “No signal detected” on the monitor when you turn on the computer., possible causes of the problem and alternatives to fix the situation. Simple alternatives first, then the more complex, but also activated in several cases. Equivalent problem: monitor writes out of range, entry not admitted (or out of range and input not supported).

What does it mean Check the signal cable, No signal detected and “No signal” on the monitor

All the messages that appear on the monitor screen have the same meaning: no video signal compatible with that input is received. The cause is the same, but the messages vary depending on your particular monitor.

• Watch cable means "Check signal cable" (the one that connects the monitor to the computer). It can also appear as “Check signal cable”.
• No it means “Signal not detected”.
• No entry says it translates as “Entry prohibition sign”.

Simple reasons why there is no signal on the monitor and how to fix them

First, on the simple and fairly common causes of the problem and the corresponding solution methods. I recommend not skipping any item, even if you are sure there is nothing wrong.

1. Cable truly disconnected or poorly connected to the monitor or to the side of the computer video card: can be accidentally touched, someone may have moved the monitor. Definitely check it out, it is not such a rare case.
2. If you upgraded the monitor or video card and then connected it using any adapter or cable with different interfaces (as an example, Display Port – HDMI, HDMI – VGA / DVI and the like), remember that this cable or adapter itself may be the source of the problem: some of them are unidirectional, some work only on certain hardware (as an example, only on those video cards that support analog output via HDMI, and such ain't produced lately). Solutions for this case: try to use the connection with the same type of ports or at least connect the digital output to the digital input, you can also buy an active signal converter. Ideally, use an original monitor cable without adapters.
3. If you have connected your computer to a second monitor, projector or television (How to connect a laptop or computer to a television), turn off your computer, disconnect the cable that goes to the TV from the video card (even if you are disconnected from the TV or second monitor), turn the computer back on and check if the No Signal Detected or Check Signal Cable problem has disappeared.
4. If the monitor menu itself has an input source selection option (Input element, Entry), open that menu and try to manually choose the input used.
5. If it is feasible, connect your monitor to another computer or laptop to rule out a malfunction of the monitor itself or its ports: if the other computer has no signal either, the problem must be with the monitor itself.
6. If your computer previously had a discrete video card, but now connect your monitor to a built-in (motherboard output), what results “No signal”, the cause may be that the integrated video is disabled in BIOS or PCI-E The priority of the video card is also set there, or an integrated processor without video.
7. Some older graphics cards cannot send the signal to the display port (in theory, the same is feasible with HDMI in addition) before the drivers are loaded (at the beginning of the startup of the installed operating system). What does it mean: if you just built a computer with such a video card or decided to reinstall it from a USB stick and your monitor is connected via the display port, it is possible that there is no signal.
8. If you bought a new monitor with a USB-C connection / Thunderbolt and connect your laptop to it, study the specifications of your laptop: not all support display output via USB-C. I also recommend using a monitor cable “native”, USB-C cables are different and some of them may not support video output / audio to monitor.

Besides, on the second of the previous points: It is common today for a user to purchase a modern graphics card that only has Display Port and HDMI, but you have a cheap old monitor that only has VGA / DVI and that's when it finds there is no signal. This can be fixed by purchasing an active converter from HDMI or DP to a standard monitor, but if the opportunity exists, I would recommend changing the monitor.

Other possible causes of no signal on the monitor and possible solutions

If everything previously described has not worked, let's move on to other possible variants, also reasonably common:

• If you have integrated video, try physically disconnecting the discrete graphics card, plug your monitor into the onboard outlet and see if that solves the problem. If it does, the possible alternatives are: additional power is not connected to the discrete video card, hardware problems with the video card, lack of power supply (actual power may be dropping due to wear and tear), problems with the slot where the video card is connected.
• The problem in question is often described as “No signal on monitor, but the computer is working”. In reality, noise from fans and lights after pressing the power button does not always mean that the computer turns on and works: if there are problems with the video card, power supply, RAM memory, the absence of connection of some power lines. to motherboard (often during independent cleaning, assembly and disassembly, component replacement) you can just turn on some power lines, but it does not start and there is no signal on the monitor, if it had been before and now there is no OS loading sound. If no other monitors appear on the same PC, is another argument in favor of this case. For more information, see separate manual What to do if your computer won't turn on.
• If your computer starts up with a monitor showing something (POST screen / BIOS, Logo) and then you get a message that there is no signal, there is probably something wrong with the image output settings you set in your operating system. True, the signal is often reported to be out of range. A feasible solution if you have Windows is to run safe mode and use recovery points, or boot from a pendrive with the same version of the OS you have installed, choose “Restore system” in the second screen from the bottom left and use the recovery points. With Windows 10, can enter recovery environment after two forced shutdowns (holding down the power button for a long time, even when it is not the safest technique). as a last resort, you can also resort to reinstalling the operating system.

Video-tutorial

I hope some of the alternatives have worked for you. If you still have to fix it, describe the situation in the comments: video card model, monitor model, how exactly did you connect, after which "No Signal" problem occurred and what you tried. Maybe, also a solution can be found for your situation.