What Does Check Signal Cable Mean?

It can be quite dreadful to see your monitor not display anything even after you have connected it to a video output port on your PC. Often times, in this situation you will see a prompt on your monitor saying “Check Signal Cable” begging the question, “What does check signal cable mean after all?” 

Basically, a check signal cable is a prompt that tells you that the monitor is not receiving any video data to output. This can particularly cause frustration if you ALREADY have the video cable plugged into both the monitor and on the output device (your PC).

In the following text I will explain the check signal cable issue and also highlight the major reasons for its causes. Fortunately, most of the common causes can be fixed easily by yourself.

So What Does Check Signal Cable Mean?

A Check Signal Cable prompt on your monitor means that the monitor is not receiving the data from the output device to its input port. Often it means that the cable is NOT plugged in properly. 

However, in some bad cases, it can mean more than just that. Sometimes the underlying cause of this issue can be a bit more serious than just an unsecured cable. 

Causes of Check Signal Cable

There are many underlying causes of the check signal cable issue. Some are quite simple to fix, others are not.

For instance, if you have a damaged video cable, this issue can easily be fixed by replacing it with a newer one for quite cheap.

However, if your core hardware like monitor, motherboard or CPU is defective, then fixing that by yourself would be quite impossible.

Following the principle of Ockham’s Razor, let us first begin by addressing the simplest fixes before moving into the more complicated causes.

1. Your PC is in Sleep or Hibernation Mode

One of the simplest causes of Check Signal Cable is that your PC could be in sleep or hibernation mode.

If you can hear the fans spinning on your PC and if the check signal cable issue has been prompted on an otherwise perfectly functioning display, then the issue could be that your PC is in sleep.

This issue can easily be fixed by pressing the Power button on your PC.

If that does not fix the issue, you can restart your PC by turning your PC off first. You can do this by keeping the Power button pressed for a few seconds.

Do note that any unsaved work will be lost when doing a hard reset. 

2. The Video Cable Not Inserted Properly

hdmi connection to laptop
Make sure the video cable is securely plugged in.

Another fairly simple cause of Check Signal Cable is a loose connection between the monitor and the PC.

Make sure that the connectors are securely plugged into both your PC output ports and on your monitor’s input ports.

3. A Damaged Video Cable

A damaged or a worn out video cable can also cause this error. 

You can check if your cable is the main culprit by using it on a different PC / device.

For instance, if you want to check whether your HDMI cable is damaged or not, you can try connecting your PC to your TV as well (most TVs have HDMI input).

If the TV also shows no signal, then there are high chances that the HDMI video cable is damaged.

Sometimes there are telltale signs of visible damage to the cable. A cut, or a rusty connector means that the cable has kicked the bucket.

hdmi cable rust
Rusted HDMI Connector is a telltale sign of a bad HDMI cable. Source: Reddit.com

4. A Damaged Video Output / Input Port

This is one of the more troublesome issues that you can come across.

A damaged video output port on your PC or a damaged video input port on your monitor can also cause the check signal cable.

Unfortunately, fixing a damaged port is not something that you can do by yourself. 

Fortunately, many PCs and monitors have a combination of video interfaces i.e HDMI, VGA, DVI, DP.

Take for instance the following motherboard, this has VGA, DVI-D, HDMI and DP ports.

Gigabyte H610M
Gigabyte H610M, LGA1700 motherboard with multiple video ports. If one is damaged, you can use the other with its relevant cable.

So in case if the HDMI port on either your monitor or on your PC is damaged, you can always use any other spare interface. You WILL, however, have to procure a separate relevant video cable for the interface of choice.

5. CPU Does NOT have an Integrated Graphics Card

One of the rookie mistakes that many make is in assuming that ALL CPUs have an integrated graphics card. That is NOT the case.

Basically, an Integrated graphics card is a MUST for the video output ports on your motherboard back I/O to work. 

motherboard video outputs ports back IO panel
Video output ports on ASUS Prime H510M-E. Back panel video output ports require a CPU with integrated graphics to work. Source: ASUS

There are many CPUs that do not feature an iGPU. Intel “F” series CPUs do not feature an iGPU. On the other hand, with AMD only “G” series CPUs feature an iGPU. 

So if your CPU lacks an iGPU, plugging your monitor to any of the video output ports on your motherboard may show Check Signal Cable.

The only workaround this is to either get a dedicated graphics card, or replace your CPU with the one that does feature an iGPU. Often in this case people prefer the former.

6. Using Motherboard Video Output Ports with Dedicated GPU Installed

If you have a dedicated graphics card installed, the video output ports on your motherboard often get disabled automatically through the BIOS.

There are good reasons for this. The graphics processing of a dedicated GPU is far more advanced as compared to that of the iGPU on a CPU. Hence by disabling the motherboard video ports, the PC is forcing you to use the more powerful dedicated GPU for video processing. You CAN enable both if you wish to through BIOS. 

Should You Connect Monitor to GPU or Motherboard
If your PC has a dedicated GPU, use its video output ports and not those of the motherboard.

7. Graphics Card Not Seated Properly

Another fairly simple issue could be a loose graphics card.

A dedicated graphics card sits on the PCIe slots on your motherboard. If it deseats itself even slightly, it will lose its functionality. Hence any monitor connected to the GPU will stop functioning.

Graphics Card
The dedicated graphics card has to be seated firmly on the PCIe slot.

You will need to open up your PC case in order to troubleshoot and fix this fairly simple issue. There is also a chassis fastening screw that holds the graphics card in place. Make sure the fastening screw is not loose.

8. Graphics Not in the Right PCIe Slot

A dedicated graphics card has specific requirements for the PCIe slot they need. They either require an x16 or an x8 slot to work.

does it matter which pcie slot I use w
PCIe Slots for adding graphics card. Not all PCIe slots are created equally. Note that the bottom x16 slot actually only has 4 lanes.

If you were to plug a graphics card into a weaker PCIe slot, say an x4 slot, then it may not work at all.

The image above shows that while PCIe slots can look the same, they can have vastly different functionality. The bottom x16 slot only has 4 lanes and hence is not suited for graphics cards. 

Note some AMD graphics cards CAN work even on an x4 slot. They do take a performance hit though.

9. Graphics Card Not Connected PCIe Power Cables

If you have recently installed a mid-high end dedicated graphics, then you may have noticed power connectors on them.

These power connectors are intended for PCIe power cables coming from the PSU. They HAVE to be connected in order for the graphics card to function.

PCie-Power w
PCIe Power Cables

PCIe power cables have to be connected to your dedicated graphics card if it is a requirement.

10. Fault with Other Components

Finally, the Check Signal Cable issue could be caused by another failing component. Here are some of the other miscellaneous considerations:

Damaged PCIe Slot

If your PCIe slot is damaged, your dedicated GPU will NOT work. You can try switching the GPU to another PCIe slot if it has the right lane count (i.e x16 or x8).

Dead CMOS Battery

A dead CMOS battery can also cause weird issues on your PC including your PC not starting at all resulting in a blank screen.

Remove the CMOS battery for 5 seconds and then put it back in.

You can try resetting your motherboard by removing the CMOS battery for a few seconds before putting it back in or by replacing it.

Motherboard and CPU Power Cables Not Connected

This is for those who have just built their new PC. Make sure that 24-Pin ATX motherboard cable and the 8-Pin ATX CPU cables from the PSU are connected to the motherboard with the CORRECT ORIENTATION.

Misaligned connectors will result in the PC not turning on and as such no signal to your monitor.

Weak Power Supply Unit

Again, a point for a newly built system. If you have installed a new powerful graphics card, make sure that your Power Supply Unit has enough rated supply power to support the new GPU.

Dead CPU / Motherboard

A very dreadful situation to be in and a consideration which should be kept to the last. 

A dead CPU or a dead motherboard could cause the check signal cable. You can try using a different monitor / TV on your PC to verify. 

Damaged Monitor

Another tedious issue. You can very this by connecting your monitor to a different PC or output device.

Final Words

Majority of the times the causes for check signal cable are simple and can easily be fixed if you understand the underlying issue.

When troubleshooting issues that deal with the internal hardware or power supply unit, make sure the PC and the monitor are disconnected from the wall socket.

Photo of author


Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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