How to use an all-in-one PC as a laptop monitor: 5 proven methods

Using an all-in-one PC as an external monitor for a laptop is a challenge that many users face. This is relevant when you need to expand your workspace, but there is no desire or opportunity to buy a separate display. However, not everyone knows that Most all-in-one PCs support external display mode, although manufacturers rarely advertise this feature.

The main difficulty is that monoblocks usually do not have video-in ports (for example, HDMI-in or DisplayPort-in), designed to receive a signal. But there are workarounds: from hardware solutions to software utilities. In this article we will analyze all the working methods, including a unique way to activate stealth mode Target Display Mode on monoblocks Apple iMac (2009–2014), which few people know about.

1. Checking the compatibility of the all-in-one PC and laptop

Before you try to connect devices, you need to make sure that your all-in-one PC is physically capable of working as a monitor. Most budget models (for example, Lenovo IdeaCentre or HP Pavilion) do not support video input. The exceptions are:

• 🖥️ Apple iMac (2009–2014 models) with port Mini DisplayPort or Thunderbolt.
• 🔌 Some monoblocks Dell (series OptiPlex And Inspiron) with port HDMI-in.
• 💻 Hybrid devices based on Windows with support Miracast or WiDi.

Check availability video-in port can be determined by the technical characteristics of the model on the manufacturer’s website or by visually inspecting the back panel. Look for ports marked In (For example, HDMI-in). If there are no such ports, software connection methods remain.

Monoblock model	Video input support	Port type	Max. resolution
Apple iMac (2009–2014)	Yes (Target Display Mode)	Mini DisplayPort/Thunderbolt	2560×1440
Dell OptiPlex 7440	Yes	HDMI-in	1920×1080
HP EliteOne 800 G2	Yes (optional)	DisplayPort-in	2560×1440
Lenovo IdeaCentre AIO 520	No	—	—

⚠️ Attention: Monoblocks with touchscreen (touch screen) rarely support external display mode. In this case, the touch panel will not work, even if the image is displayed.

2. Connection via cable: HDMI, DisplayPort, USB-C

If your monoblock is equipped with a port HDMI-in, DisplayPort-in or Thunderbolt, connection is as simple as possible. You will need:

• 🔌 Suitable cable (e.g. HDMI-HDMI or USB-C to DisplayPort).
• 🖥️ Laptop with output HDMI-out, DisplayPort-out or USB-C/Thunderbolt.
• ⚡ Power supply for the candy bar (if it does not turn on automatically).

Step by step instructions:

1. Turn off both devices.
2. Connect the cable to the port HDMI-out on a laptop and HDMI-in on a candy bar.
3. Turn on the monoblock and switch it to external display mode (usually with the Source or Input on the control panel).
4. Turn on your laptop and press Win + P, then select a mode Expand or Duplicate.

Turn off both devices|

Check port compatibility|

Use a high-quality cable (length no more than 3 m)|

Select the correct display mode (Win + P)

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For monoblocks Apple iMac (2009–2014) the process is different:

1. Connect your laptop to the port Mini DisplayPort or Thunderbolt on iMac.
2. Turn on iMac and press Command (⌘) + F2 - this activates Target Display Mode.
3. Screen iMac should display the picture from the laptop. To exit the mode, press again Command (⌘) + F2.

⚠️ Attention: On iMac 2015 and newer Target Display Mode doesn't work. This mode is also not available on models with display 5K.

3. Wireless connection: Miracast, WiDi, AirPlay

If a cable connection is not possible, you can use wireless technologies. Basic standards:

• 📶 Miracast (built into Windows 8.1/10/11 and many monoblocks on Android).
• 🖥️ WiDi (Wireless Display) from Intel (outdated, but still found).
• 🍎 AirPlay (only for ecosystem Apple).

Instructions for Miracast:

1. On the candy bar, activate the signal reception mode (for example, in the settings Wireless display or Screen Mirroring).
2. On a laptop, click Win + K and select the name of your all-in-one PC from the list.
3. Confirm the connection on both devices.

For Apple devices:

1. Make sure the laptop (MacBook) and monoblock (iMac or Mac mini) connected to the same network Wi-Fi.
2. On the candy bar, turn on AirPlay Receiver in settings Sharing.
3. On your laptop, open Control Center → Screen Mirroring and select the all-in-one.

4. Use of specialized programs

If hardware methods are not suitable, you can use programs for remote control or screen broadcasting. Popular solutions:

• 🖥️ SpaceDesk (free, supports Windows And Android).
• 🌐 Duet Display (paid, optimized for iPad, but also works with monoblocks).
• 🔄 Splashed (alternative for macOS).

Setting example SpaceDesk:

1. Install SpaceDesk Driver to laptop (official website).
2. Install SpaceDesk Viewer on a candy bar (if it is on Windows) or use the browser version.
3. Start the server on your laptop and connect to it from your all-in-one PC by entering local IP address.

Advantages of the software method:

• ✅ Works even without video-in ports.
• ✅ Supports touchscreen (if the candy bar is touch-sensitive).
• ✅ You can connect several devices at the same time.

Disadvantages:

• ❌ Image delay (lag) at low Wi-Fi.
• ❌ Requires software installation on both devices.

How to reduce latency in SpaceDesk?

Use a wired connection via Ethernet instead of Wi-Fi.|

Set in settings Quality: Balanced instead of High.|

Close resource-intensive applications (such as a browser with many tabs).|

Disable hardware acceleration in the program's graphics settings.

5. Connection via USB (for all-in-one PCs that support USB Display)

Some monoblocks (for example, ASUS Zen AiO or MSI Pro 24X) support technology USB Display, allowing video to be transmitted through the port USB 3.0/Type-C. This requires an adapter USB-to-HDMI or USB-to-DisplayPort, as well as the driver DisplayLink.

Instructions:

1. Connect the adapter to USB 3.0 monoblock port.
2. Install the driver DisplayLink with official website.
3. Connect the adapter to the laptop via HDMI or DisplayPort.
4. In the laptop screen settings (Win + P) select mode Expand.

Limitations of the method:

• 🔌 Required USB 3.0 (blue port) - USB 2.0 doesn't fit.
• 🖥️ Maximum resolution is usually limited 1920×1080.
• ⚡ There may be a delay when watching videos.

6. Alternative solutions: docking stations and adapters

If none of the above methods are suitable, consider using docking stations or video adapters. For example:

• 🔌 USB-C Dock (For example, Dell WD19 or CalDigit TS4) - allows you to connect a monoblock via Thunderbolt 3.
• 🖥️ HDMI repeater (if the monoblock has HDMI-ARCwhich sometimes works like HDMI-in).
• 📡 Wireless HDMI Kit (For example, Nyrius ARIES Prime) - for wireless broadcasting with minimal delays.

Example of connection via a docking station:

1. Connect the docking station to your laptop via USB-C/Thunderbolt.
2. Connect the all-in-one PC to the docking station with a cable HDMI or DisplayPort.
3. Turn on the all-in-one and select the appropriate signal source.

⚠️ Attention: Docks with support MST (Multi-Stream Transport) allow you to connect up to 3 monitors simultaneously, but in this case the monoblock will be considered one of them.

Common mistakes and their solutions

When connecting an all-in-one PC as a monitor, users often encounter typical problems. Here are the most common ones and how to fix them:

Problem	Possible reason	Solution
There is no image on the candy bar	Incorrect signal source selected	Click Input/Source on the all-in-one and select the desired port
Flickering or artifacts	Damaged cable or incompatible resolution	Try a different cable or change the resolution 1920×1080@60Hz
The all-in-one is not detected over Wi-Fi	Disabled Miracast or different networks	Turn on Miracast in settings Windows and connect both devices to the same network
Target Display Mode doesn't work for iMac	Unsupported model or version macOS	Update macOS or check model compatibility at Apple website

If the all-in-one still does not work as a monitor, check:

• 🔌 Food: some monoblocks require a separate power supply even when connected via USB-C.
• 🖥️ Drivers: update the video driver on your laptop (especially if you use NVIDIA or AMD).
• 📋 BIOS settings: On some laptops you need to enable Multi-Monitor Support in BIOS.

FAQ: Answers to popular questions

Is it possible to use a monoblock Lenovo IdeaCentre how's the monitor?

Most models Lenovo IdeaCentre do not support external display mode as they do not have ports HDMI-in or DisplayPort-in. The exception is some business models (for example, ThinkCentre Tiny-in-One), which can be connected via a docking station.

Why does the monoblock say “No signal” when connected via HDMI?

There are several reasons:

1. The cable is damaged or does not support the required resolution (try another cable).
2. The external display output is not activated on the laptop (click Win + P and select a mode).
3. The monoblock is not switched to signal reception mode (press Source on the remote control or panel).

Is it possible to connect an all-in-one PC to a laptop via USB 2.0?

No, video signal transmission requires USB 3.0 (blue port) or USB-C/Thunderbolt. USB 2.0 has insufficient bandwidth for video transmission.

How to connect a monoblock HP Pavilion how's the monitor?

Models HP Pavilion usually do not support video input. However, some monoblocks of the series EliteOne have a port DisplayPort-in. Check the technical specifications of your model on the website HP.

Will the all-in-one touch screen work when connected as a monitor?

It depends on the connection method:

• 🔌 By cable (HDMI/DisplayPort): the touch screen will not work.
• 📶 Via Wi-Fi (Miracast/AirPlay): touch input may work, but with a delay.
• 🖥️ Through programs (SpaceDesk): supported touchscreen, but requires configuration.