Many users are faced with a situation where the desktop of their main computer requires expansion, and buying a new display seems like a waste of their budget. At such a moment, equipment that is already at hand comes to the rescue - your old one or even a new one laptop. Contrary to popular belief, most modern models are equipped with video outputs, but not inputs, which makes direct cable connection impossible without additional tricks.
There are several working methods that allow you to solve this problem using software or using specialized equipment. The choice of a specific method depends on your technical requirements, the availability of free time and the desired image quality. Some methods provide minimal latency, ideal for gaming, while others are better suited for working with documents or watching videos.
Why can't you just connect the HDMI cable directly?
The first thing a user who wants to combine two devices faces is trying to connect them using a standard HDMI cable. In 99% of cases, this operation does not work and the laptop screen remains black. The reason lies in the architecture of the video outputs: the port on the device body is intended solely for transmitting the signal outside, and not for receiving it.
The internal circuitry of the video controller does not support the video signal input function through this connector. If you connect a cable between the system unit and the laptop, you will simply connect the two outputs to each other, which is technically meaningless and potentially dangerous for the motherboard. The only exception is rare gaming models that support specific capture technologies, but they are extremely rare.
You need to look for alternative paths that use network protocols or external hardware modules. Understanding this fundamental difference between a signal's input and output will save you time and unnecessary fiddling with wires. Without this knowledge, any customization attempts will be doomed to failure.
Using the standard Project to This Computer feature
The most accessible and free way to implement your plans is built into the operating system Windows 10 and Windows 11. This feature, called Wireless Display or projection, uses Miracast technology to transmit images over a local network. This solution does not require the purchase of additional equipment and is ideal for office tasks.
To activate monitor mode, you need to go to Settings → System → Project to This PC. If the required options are not available, you will need to go to Additional options and install the component via Control Panel → Programs and Features → Turn Windows features on or off. Find the “Wireless display” item and activate it with a checkmark.
After installation on your main PC, press the keyboard shortcut Win + Kto open the device search menu. Your laptop will appear in the list. Select it and the image will start streaming. It is important to note that for stable operation both devices must be on the same Wi-Fi network.
Display modes can be flexibly configured: from duplicating the screen to expanding the workspace. However, it is worth considering that even with an excellent router, the signal delay can range from 50 to 150 milliseconds. This makes this method unsuitable for dynamic games, but quite comfortable for working with tables or a browser.
- Wireless Windows Projection
- External HDMI Capture
- Third-party software over the network
Hardware solution via video capture card
If minimum latency and high picture quality are critical to you, software methods will not work. In this case, the only correct solution would be to use an external video capture cards. This is a compact device that converts an analog or digital video signal into a data stream that is understandable to the operating system like a webcam.
The connection process is as follows: cable HDMI from the system unit is inserted into the Input of the capture card, and the Output of the card is connected to the USB port of the laptop. The system will identify the device as a camera, and to display the image you will need to launch a special application, for example, the standard “Camera” in Windows or OBS Studio.
The advantages of this method are obvious: you get a picture with a refresh rate of up to 60 Hz and Full HD resolution without significant delays. This allows you to even play light online games or do video editing. The cost of such adapters starts from modest amounts, which makes them affordable for most users.
⚠️ Attention: When purchasing a capture card, be sure to check the supported resolution. Cheap models often claim 4K support, but only deliver 720p at low frame rates, which will make the picture blurry.
To adjust image quality in the capture application, you need to manually set the video stream parameters. Make sure the bitrate is set to the maximum value available on your USB bus. Otherwise, you risk getting compression artifacts when objects move quickly on the screen.
☑️ Setting up a video capture card
Comparison table of connection methods
To help you choose the best option, we have prepared a summary table that compares the main characteristics of each of the methods considered. Please note differences in latency, hardware required, and data quality.
| Method | Delay | Quality | Cost | Ideal for |
|---|---|---|---|---|
| Windows projection | High | Average | Free | Work, presentations |
| Video capture card | Low | High | From 1000 rub. | Games, editing |
| Third party software | Average | Network dependent | From 0 to 3000 rub. | Remote access |
As can be seen from the data, the choice depends on priorities. If you just need more space for text editors, a free Windows feature will do the job just fine. For gamers, the only option is hardware capture, which ensures smooth images.
What is the difference between USB 2.0 and 3.0 for capture cards?
USB 3.0 is required for Full HD 60fps transmission. On port 2.0 there will not be enough bandwidth, and the picture will freeze or be jerky.
Third-party programs for remote access
In addition to the built-in tools, there are many specialized utilities that optimize the transmission of video streams over the network. Programs like Spacedesk or Duet Display use their own compression algorithms, which often work faster than standard Miracast. They allow you to turn your laptop into a monitor even via the Internet.
Installation of such software requires drivers on both devices. After connecting to the same network, you will see a list of available displays in the program settings. A special feature of these solutions is the ability to adjust sensitivity to packet loss, which makes the picture stable even with a weak Wi-Fi signal.
Some of these services offer paid subscriptions to get additional features, such as support for touch panels or higher resolutions. Free versions usually have frame rate limits or add a watermark to the image. Carefully study the functionality before using it.
It is important to understand that the load on the laptop processor when using third-party software will be significantly higher than when using hardware capture. This is due to the need to decode the video stream in real time. If the laptop is old, it may start to overheat or slow down.
⚠️ Attention: When using Wi-Fi software solutions, make sure that the router operates at 5 GHz. The 2.4 GHz frequency is often congested and does not provide enough bandwidth for smooth video.
To minimize latency in the program settings, disable hardware acceleration if it causes artifacts, or vice versa, enable it if the processor is 100% loaded. Experiment with these settings.
Setting resolutions and refresh rates
After successfully connecting the image, you need to correctly configure the display settings to get the clearest picture possible. Go to Screen Options and select the connected laptop. Here it is important to set the native resolution of the laptop screen to avoid blurring of text and icons.
The refresh rate also plays a role. If you are using a wireless connection, try lowering the frequency from 60 Hz to 50 or 30 Hz. This will reduce the load on the network and can stabilize the picture by removing micro-freezes. For a wired connection via a capture card, always select the maximum value supported by the device.
Don't forget about scaling. On high resolution (2K or 4K) laptops, text on the main PC may appear too small. In the section Scale and layout You can increase the size of interface elements to 125% or 150%. This will make the work more comfortable for the eyes.
Correct scaling and resolution settings are critical to text readability. Always set your screen to the native resolution, even if it puts a strain on the network.
Possible problems and solutions
Sometimes the connection does not occur or the image does not work correctly. One common cause is that network ports are blocked by Windows Firewall. Check your security settings and allow incoming connections for the projection or capture application.
If the picture is delayed, try rebuilding the router closer to the devices or using an Ethernet cable to connect both computers to the network. A wired connection is always more stable than a wireless one. Also check if the network is congested with other devices downloading large files.
If you are using a capture card, if there is no image, check that the device is selected as the active source in the viewer. Sometimes drivers require reinstallation or updating. Make sure the HDMI cable is not damaged and is firmly inserted into the connectors.
Sometimes the problem lies in the video driver version. Outdated video card drivers may not handle streaming video correctly. Go to the website of your video card manufacturer - NVIDIA, AMD or Intel — and download the latest version of the software.
⚠️ Attention: If, when connecting via Wi-Fi, the image “scatters” into squares, this is a sign of channel overload. Switch to a wired connection or reduce the transmission resolution.
FAQ: Frequently asked questions
Is it possible to connect a laptop to a PC via HDMI without additional devices?
No, that's impossible. The HDMI port on a laptop is an output port, not an input port. To transmit the signal you will need either a wireless projection or an external video capture card.
What is the latency of Windows wireless projection?
The delay is usually from 50 to 150 ms, depending on the quality of the Wi-Fi router and the network load. This is too much for gaming, but quite acceptable for work.
Will any video capture card be suitable for this purpose?
Any USB capture card that supports HDMI will do. However, for games, choose models with support for 60 Hz and USB 3.0, otherwise the picture will twitch.
Can a laptop be used as a monitor if it is turned off?
No, the laptop must be turned on and working. An operating system is required to decode the video stream or display the signal from the capture card.
What to do if the laptop does not see the main computer?
Make sure both devices are connected to the same Wi-Fi network. Check your firewall settings and make sure the projection feature is enabled in your system settings.