My PC does not give an image - reasons and solutions

As in any problem, there are various causes or reasons why our PC does not give an image. Today we will try to cite all those possible problems and add a solution, from a simple loose connection to a hardware problem. Which one will have touched you?

Index of contents

Identify the problem

The first of all will be knowing how to identify where the problem is, since this failure can range from nonsense to the failure of one or more components on our PC.

Does your PC run well until the power is out? The first and main reason may be this, if my PC does not give an image after a blackout it can basically mean two things: that the BIOS has been deconfigured or that some component such as memory or CPU has been damaged.

Whether it is a laptop or a desktop computer, if the PC turns on, and the display does not give an image, it may also be due to a hardware failure, a failure in the display connections or even dirt on the component contacts.

On the other hand, if we try to turn on the screen and the logo of the manufacturer of the same does not appear or the backlight of the panel seems to not even turn on, then it could be a failure of the monitor.

Connections or monitor failures

Before we start to open our equipment and start fiddling with components at random, we are going to rule out possible connection failures of our monitor or panel failure.

As we know, monitors are not timeless, and with tampering, power outages, or due to weather, your panel degrades and can break like anything else. As my own experience, I tell you that I had a cheap Samsung monitor that with just 1 year of life broke overnight.

Connect video to dedicated card not on board (desktop)

Let's check the connections, first of all. We should all know that our PC does not give an image if it has a dedicated graphics card and that we are using it is the one on the board. We may have inadvertently connected the monitor to the motherboard's own video port. This can happen when we buy a new PC and we are not used to the ports, or when we install a dedicated card and do not check the connections.

Manual selection of video source

Another problem that we can run into is that our monitor does not automatically select the video source. That is, we connect the monitor with VGA, DVI, HDMI or DisplayPort to our PC and in its firmware it has a fixed input selected by default. The result will be that the screen lights up black with the message "no signal" next to the name of the connector selected by default. In this case what we will do is access the video options of the monitor and select the connector to which we have connected the video, easy. This happened to us recently with a ViewSonic that we analyzed.

Test the monitor on another PC

It can be directly on a laptop, but if you have already discarded the previous failures and when you give the power button the screen is still black, it is a problem with it. In this case we must test the screen on a PC that we do know works well, and it should automatically turn on, which can be a laptop via HDMI (all have). If the screen does not turn on and the PC is on, the fault is with our monitor, the end of the story.

Hardware failures of our PC

Having ruled out errors on the screen, we have to focus on our PC, although we will leave the laptops for a later section, despite the fact that the procedure is almost the same.

Does your PC turn on? Power supply problem

If my PC does not give an image, but the tower does not turn on either, we have a problem with the power supply. We will know that a PC is turned on as soon as we hear noise on the hard drive if it is mechanical and fan noise. If none of this happens it is that the source does not deliver power correctly to the board.

Another sure way to know if your computer is active is to touch the CPU cooler. If it is cold, it means that the processor is not working, which may be due to it not starting or being broken. Finally check that the power button on the chassis works, it may have been disconnected or the cable has broken

First of all verify that the switch that carries the source behind is in the on position.

In this case, what you would have to do is check that the different connection cables give voltage, which can be 3.3, 5 or 12 V depending on what type of cable it is. We leave you here the diagrams of each header.

Another quick way to do this is to test the source on another motherboard, or test our motherboard with another source.

How to find out which component is failing with BIOS messages

We arrived at this assumption by seeing that our computer turns on normally (or not so normally) and the screen is still off. In it, the backlight turns on with the nice message that there is no signal and it turns off again. This can be due to a lot of different problems, but there are three ways to identify them:

BIOS speaker

We have placed them from older to newer, since every board has in its F_Panel a header to connect the small starter speaker. The function it performs is very important, since it notifies, through a succession of beeps, a possible error or malfunction during the startup of a computer.

Unfortunately, few teams currently have it and it is something that would be very useful for a user with little knowledge, since interpreting the Debug LED is somewhat more complex. In this table we leave what each beep means:

Undoubtedly the most common in this case will be the long beep with RAM memory failure, the 5 CPU beeps or errors in the graphics card, which is almost always due to poor connections in its slot.

Boot Post

Then, the newer mid-range boards began placing a series of LEDs that marked the BIOS check on the various components. This system simplifies the speaker system, although it provides less information than it. It was first used when UEFI BIOS were implemented.

Normally they are 4 LEDs arranged as seen in the image: RAM, CPU, GPU (graphics card) and Start. When a PC starts up, the BIOS checks all the components, so the LEDs advance until reaching the Start-up LED. If one of the above remains on or restarts once one of these three is reached, the fault will be in that component.

Debug LED Board

Finally, the current high-end panels have a two-digit display that always marks events produced in the hardware using alphanumeric codes. It not only reports errors, but also processes carried out by the UEFI and the components. In the following images we leave what each code means. An identical table is included in all the board manuals as it is a universal system.

Clean components and ensure good contact

As you can see, knowing the reason why the PC does not give an image is becoming increasingly complicated. So let's relax a little and do something simple but wise, which is to open our PC and clean its components. We recommend having these tools on hand:

• Screwdriver Eraser to clean the contacts of the memories and GPU Brush to clean the plate Discharge of static electricity by touching metal or putting on latex gloves

This is very important, because most problems are solved simply by removing, cleaning and replacing components. Let's make sense, that is, if the board gives us an error message in RAM for example, let's focus on that component.

The most daring can remove the heatsink, the CPU and verify that all the contacts are in perfect condition, without any bent. Likewise, we recommend placing thermal paste if the one they have is very hard or worn.

Clear CMOS on the board

If we have removed the components and put them back and everything remains the same, it is time to do the next step, which is to reset the BIOS, which is called Clear CMOS.

CMOS is the chip that stores the BIOS settings of our PC. It is possible that, during a power outage, oveclocking or for having modified something that we should not have, the parameters are not correct and the PC cannot boot. What we have to do is return it to the factory state. There are three ways to do this:

With the "CLEAR CMOS" button

Almost all current boards have a button on the port panel with this name or similar (not to be confused with BIOS Flashback, which is to update it). This button can also be inside, on the board itself.

• We are going to turn off the board, and unplug the power We leave this button pressed for 5-10 seconds We start the board and the BIOS will reset

With the jumper on older boards

It is the same as the previous button, but it is inside the board, usually near the stack and distinguished by having three pins and a plastic bridge. Next to it will be CLRPWM, PASSWORD, CLEAR CMOS or similar.

• We turn off the board and unplug the power We take the jumper off pins 1-2 and puncture it on pins 2-3 for 5-10 seconds We put it back where it was We turn on the board

Removing the battery for a few minutes and putting it back

Basically it is to do the same, but in a rough way. The battery that the boards have is used to constantly power the CMOS chip that stores the BIOS settings. By removing this, we are going back to the factory parameters of the chip, so it is a CLEAR CMOS in short.

If a board has been unused for a long time, the battery may have been exhausted, we will notice it because when it starts up, it always returns to the factory state and does not let us continue with the start-up. So we should buy one and put it on.

Check the board components

We hope that with the two previous steps we have managed to solve the problem that the PC does not give an image, in 80% of cases it is so. If, on the other hand, the PC starts up, but the screen does not turn on, it is time to look component by component.

RAM

We will know that it is a problem of this when the debug LED gives us a code 50 - 55, 3 beeps in the speaker or the Post stops at "RAM". If it is not a memory that we have just installed, it is possible that some module has been broken, so you have to try them separately.

• We take one by one or we test them separately We do it in different slots To be safer, we test them on another PC

Be careful, because it is also possible that we have wrongly activated the XMP profile of the memories in the BIOS, we have entered an incorrect voltage or frequency. With this, the screen will not give an image either, and the board will be continuously restarting. In principle this is not harmful to RAM, but beware of latencies, because the modules could be loaded.

Graphic card

This problem is a little less mechanical than the previous one, and the fact that the boot post is left in "GPU" does not mean that the error is in it. In any case, what we must do is verify that the dedicated GPU is well placed in its PCIe slot, always in the first one that will be the one that works at x16.

• If our PC is Intel or AMD with integrated graphics, we are going to remove it and connect the monitor to the video port of the motherboard itself. If it works, it may be a problem of the dedicated GPU or the PCIe bus in which case the Debug LED will not go beyond the code 90. We test the graphics card on another PC if possible to verify

CPU or motherboard problem: update BIOS

When the CPU is broken it may not even boot, or it is continually rebooting without going past the CPU LED in the post. The clearest way to know that it does not work is that the heatsink at its base is completely cold.

If the CPU is new and compatible with the board, and we know that the board is fine, what we should do is update the BIOS to its latest version to ensure compatibility. For this there are three methods, from the BIOS itself in UEFI, through a USB with BIOS Flashback or from software in Windows.

If this does not work, it will be best to throw out the warranty, because it is rare for a user to have two CPUs or two boards at home to test. Also, if the board is defective, it would be best not to put another CPU, since we could break it too.

My laptop screen doesn't turn on

Everything written above is applicable to laptops, although it is clear that testing component by component here is much more complicated. There is a fairly recurring method that usually works for older laptops with removable batteries:

• We remove the battery and the power plug We keep the start button pressed to discharge the circuits (60s for example) After a while, we connect the laptop directly to the power plug and without the battery

Clear CMOS to a laptop

If we want to do a more forceful CLEAR CMOS, we would have to open the laptop and look for the jumper with this name. Or remove the battery and then insert it, just as we did with a desktop PC board.

With this the BIOS will return to the factory parameters and possibly return to normal.

Update BIOS

Today's notebooks have an internal function to update the BIOS easily and directly from the network. For this we must enter the BIOS itself and locate this function in the Tools section or similar with an available internet connection. This is best looked at in the instructions, as each manufacturer and model can change.

It is also possible to do it through software from Windows, if the laptop in question offers this possibility. For this we will visit the team support section and look for the application.

Check components, test external monitor and display connection to motherboard

Sometimes, after opening and closing the laptops the connector ends up breaking, it is normal after a long time of use and that we can only verify by opening the laptop or taking it to a technical service.

The best way to test if the laptop screen is broken is to connect it to an external monitor or TV through the HDMI port that the computer will carry or the VGA if it is older. If in this we receive an image normally, the fault is the integrated screen.

We only have the typical process that in this case is reduced to reviewing the memories and cleaning the components well.

Conclusion on my PC does not give image

It is always difficult to make this type of tutorials, posts or whatever you want to call them, since there are an infinity of problems that can occur and it is impossible to treat each and every one of them separately.

However, we believe that with these guidelines and leaving aside the fear of opening a computer or exploring the hardware of a PC, you could all find out what the problem is with your computer. The key solution is almost always to do a CLEAR CMOS or change RAM memory, since it is less common for motherboards or CPUs to break without further ado except for blackouts or heavy use.

Links that may interest you:

Without further ado, we hope that some of these solutions have helped you solve the problem if your PC does not give an image. If your problem persists, you can ask us in the comments below or open a thread in our Hardware Forum. Four eyes see more than two, and 100 much better.