The situation when your computer cannot see the monitor via HDMI, DVI, or VGA usually occurs at the most inappropriate times. Suppose you press the power button, and the PC starts humming as usual, but you see a black screen instead of the welcome window. Reboots don’t help, and you cannot type anything, run an application, or watch a movie just because the monitor is not visible. In the best case, you can see “No signal” or a similar message reporting an error. After a few seconds, the backlight goes off, and the problem remains unsolved.
There are various reasons for this malfunction, and we will tell you about them in this article. In most cases, it is hardware-type, i.e., not related to the operating system settings but the hardware and the monitor. This unpleasant situation can happen to everybody, whether you have an inexpensive or prestigious monitor or you are an advanced or novice user. We will tell you what happens when the monitor doesn’t connect to the computer and shows the “No signal” error. Follow the step-by-step instructions for troubleshooting and you will get your display back up and running!
The leading causes of malfunction
In almost 99% of situations with the inability of the computer to see the monitor, the problem is related to the computer. It refuses to transmit the video signal to the display for some reason. The show notifies you of the inability to display the signal and then goes into standby mode.
When you press the power button, the coolers in the system unit start humming. This is a good sign because the power supply is powered correctly. But it is still unclear if the motherboard or video card is working properly. Since the device transmitting the signal to the monitor is not working, you see the “No signal” notification on the computer screen instead of the image. The display is usually intact; you can verify this by connecting the device to another PC or laptop.
The cause of the “No signal” error can be eliminated in several ways. The easiest one is to check if the cable plugs are tightly connected to the pins of the computer and the display. An incorrect connection may also cause the problem. You can fix it by clicking the cable properly. Other possible causes of the computer’s failure to see the monitor may include the following:
- The damaged power supply. The device may have enough power to make the coolers work, but there is minimal voltage for other components, and the motherboard or graphics card cannot be turned on;
- The failure of the RAM. The card can get dusty, or the pins can oxidize or just come out of the socket. As a result, your monitor is completely invisible to the computer;
- The failure of the graphics adapter. A graphics card is a complex device that can fail for almost any reason, from overheating to a voltage spike on the pins;
- The failure of the entire motherboard. Fortunately, this happens rarely, but if it does, you’ll probably have to buy a new motherboard.
Finally, if there’s no signal on the monitor after your PC is assembled, the problem may be related to the display. Please don’t rush to buy a new device: first, follow our step-by-step instructions to solve the problem.
Your first steps
Let’s consider the software problem first. No operating system is protected from accidental malfunctions. Fortunately, such issues can be fixed by the operating system itself.
This solution takes quite a long time, up to several minutes. As a result of such a delay, the signal from the computer does not come to the monitor. That is why you see the “Monitor no signal” notification on the screen. The operating system usually solves the problem in 2-5 minutes.
Wait for at least ten minutes before rebooting your computer and disconnecting it from the power supply. Then try to determine the reason for the lack of the signal using this algorithm:
- If the new computer does not see the monitor, connect the device to any other available computer to see if the display is functioning.
- Power down the computer, then turn it back on as usual. If there is no sound after turning your PC on, the problem is related to a motherboard, RAM, or video card failure.
- Make sure that the system hard drive is securely connected to the motherboard. The HDD and motherboard cable should fit adequately into both connections. You may also try replacing the cable with the new one.
- Check the rotation of the coolers inside the system. If there is no sound, your power supply is damaged and does not supply voltage even to the fans. Ensure the power supply is connected correctly: the power cord is plugged in, and the toggle switch on the back panel is in the “On” position.
- Try to connect the display to a video card integrated into the motherboard instead of a discrete one. After starting, you may probably see the picture on the screen. It means that the problem is fixed completely. Connect the graphics adapter to the pins tightly. If you see signs of burning on the motherboard, replace it with the working one.
- Make sure that the problem is not related to the memory cards. They sometimes fail due to overheating. Clean RAM from dust regularly and do not allow the dirt to stick there or the humidity to increase inside the system unit. Start by checking the pins: you should clean them, try to swap them, and insert them one by one. Don’t forget to turn off your computer before each new operation.
You will probably find a way to fix the problem already at the stage of checking. If not, take a closer look at the monitor that is not visible to your PC. This is important if nothing is visible on the screen at all, even without any warning notifications:
- If there is no signal on the monitor when you turn on the computer, start by unplugging the device from both the power outlet and the PC and reconnecting it to the power outlet. If you see the “Cable is not connected” notification, your display is functioning, and you just need to connect the cable from your PC to the monitor more carefully.
- Try connecting the display to any other working computer or laptop with a suitable cable. You can also perform the reverse action: connect the system unit or laptop to another monitor.
The failure of the backlight system of the screen is unpleasant but harmless. Take a powerful flashlight and shine it on the black screen. If you see a dim but still familiar picture, the problem is in the backlight. You can replace it with the working one in any service center quickly and relatively inexpensively.
Check the monitor power cable
The display, like any other computer equipment, works (and can be seen by the computer) only when it is supplied with sufficient voltage. In most cases, the monitor is powered by a separate cable plugged into a household outlet. This may be why the new PC does not see the monitor. The power cord may be disconnected. Plug it more tightly into the pin on the display housing, check whether the plug is plugged into the socket, and ensure it is functioning. If necessary, you can tape the cable to the device, but remember that this is the temporary method of solving the problem until you can make a simple complete repair.
Pay attention to the cord. Clean the contacts using the alcohol-based solvent and check the cable for damage: there should be no fraying, cuts, or breaks in the outer layer. If you find such problems, the best solution is to replace the cord with a new one. Try to connect the monitor to the network with another cable.
Check the cord going from the video card to the monitor
The second cord from the PC to the display also needs thorough checking. You may find damage to the cord insulation, loose contacts, and other problems. If the monitor shows the “No signal” notification when you turn on the computer, connect the cable more tightly to the appropriate pins or replace it with a new one. As in the previous case, you can use duct tape. It is strictly forbidden to fill contacts with adhesive compositions.
You may have connected the monitor to the video card using the adapter. In this case, it is necessary to check the operability of this equipment. As a rule, cheap adapters fail very quickly. If possible, connect the display directly to the same or another computer.
If you can see the image on the screen after all the above actions, you can finish reading this article and move on to troubleshooting the problems that made it impossible for your computer to see the monitor. But if you cannot, move on to the next section.
Check the video card
This device allows the signal to be sent to the screen. If the graphics card fails, you cannot see pictures on display, even if all the other components are delicate. We have already listed the most common causes of PC failure above. Now let’s move on to the details.
To ensure the problem is not related to the video card, turn off the computer, remove the side panel, and carefully disconnect the graphics adapter from the motherboard. After that, carefully clean the contacts with absorbent cotton with a degreasing solution, removing traces of dust and oxidation. If you see traces of burning on the surface, you must immediately replace the video card and repair the contacts. There is nothing else you can do in this situation.
Your motherboard has a built-in video card. It is low-performance but is responsible for sending a video signal to the monitor. Try connecting the display to this connector and turning off the PC beforehand. If you can see the image on the monitor after turning the computer on, you still have to replace the discrete graphics adapter. Another common problem is the incompatibility of video cards working simultaneously. To fix it, disable the video card not currently used in the BIOS.
Of course, the video card must be connected to the connectors properly, not falling out of the slot, as these factors can lead to the fact that there being no signal on the monitor after assembling the computer. Carefully adjust the video card’s position and ensure that it is connected to all required slots. If the problem is still not fixed, move on to the next step.
Check the RAM
You can find out about the breakage of the RAM by the specific signal produced by the speaker built into the motherboard. There is a simple way of troubleshooting.
Remove the system unit’s side panel and remember the memory slots’ location. Remove the memory sticks, but don’t forget to turn off your computer beforehand. Put the slots back one by one. Start the operating system after each of these manipulations and watch the changes on the monitor.
As a result, you may discover why the monitor does not see the computer and shows the “No signal” notification. Try to remove the damaged memory stick, install a working one in its place, and check if the display started working. You can also leave the functional boards in their places and buy new modules to replace the damaged ones.
Check the power supply
The primary contact supplying voltage from the power supply to the motherboard and other connected components has 24 pins you need to check. It is also essential to check the second contact with 4 or 8 pins.
Disconnect both pins from the motherboard and check them carefully. If you see signs of oxidation, clean the metal details with a grease remover. If there are traces of burning instead of an oxide film, stop using the damaged power supply immediately and buy a new one.
Check the hard drive connection
The system hard drive can be why the monitor stops seeing the computer. Check whether both loops, the one that transmits information and the one that provides power, are securely connected to the HDD. You can also plug in a new working cable or connect to the free connectors on the motherboard. There are usually at least four of them. It is necessary to turn off the computer beforehand.
Check the monitor’s operating mode
The problem may also be caused by wrong or incorrectly specified settings. If you press any of the buttons on the bottom of the monitor, find the manual provided by the manufacturer and set the correct operating parameters. Perform a complete reset if possible. The picture should appear on the screen when you turn on the computer again.
Reset the BIOS
The following possible reason for the problem is incorrect BIOS settings. You can fix it by resetting the settings to the original ones. To do this, follow these simple instructions:
- Please turn off the PC using the power button and unplug it. Instead of the last action, you can move the toggle switch of the power supply on the back panel of the PC to the inactive position.
- Remove the side panel of the system unit. Clean up inside it if necessary: remove dust, traces of dirt, and unnecessary items.
- You may need to disconnect the power supply’s CPU, graphics card, and other accessories to simplify access to the motherboard. Do this if necessary but remember the connection order.
- Lay the system on its working side up to make it easier to do the following manipulations.
- Find a large, round, and shiny battery. It is usually located in the center of the motherboard but may be displaced to one of its corners.
- Remove the battery using thin tweezers, knives, slotted screwdriver, or awl. Try not to damage the battery or the motherboard. In some cases, the battery is held in its place by retaining clips, which should be bent beforehand.
- When you remove the battery, the CMOS module responsible for the BIOS settings will be de-powered, leading to a reset. As a rule, it is enough to keep the computer in this state for a couple of hours, up to a day, for a guaranteed reset. Don’t insert the battery immediately after removing it because the settings will not have time to reset. If you don’t want to wait, just connect the contacts in the battery connectors: one is on the side, and the other is on the bottom of the platform.
- After a certain amount of time, insert the battery back in. After that, you can assemble the system unit, apply voltage, and check if the monitor has become visible to the computer.
Never perform manipulations related to the connection or disconnection of components without de-powering your PC first. Otherwise, you risk much more severe problems than the problem with the monitor, including the hard drive and motherboard burnout.
After reassembly, check if the power supply is connected correctly to all internal components. Otherwise, even if the reset was performed successfully, the computer may not give the signal to the monitor again.
If removing the battery is impossible, you can perform a reset directly from the BIOS menu or call a specialist. It is a bad idea to disassemble the motherboard at home altogether.