Which USB-C cable for a monitor? A comprehensive guide – USB 4 and USB 3.2.

1. Introduction

The USB‑C standard has become the norm in modern devices, offering fast charging, data transfer and video output – all through a single cable. More and more monitors support USB‑C connections, which simplifies your workstation setup by eliminating the need for multiple cables such as HDMI or DisplayPort. However, not every USB‑C monitor cable works the same way. There are different versions and specifications that can affect image quality, compatibility and functionality. In this article, we’ll explain which USB‑C cable for a monitor to choose to ensure the best image quality and work performance.

2. Does every USB‑C cable support a monitor?

Not every USB-C cable for a monitor can transmit video. For the monitor to receive a video signal, both the source device (e.g. laptop, tablet) and the cable must support DisplayPort Alternate Mode (DP Alt Mode).

Types of USB‑C cables:

• USB‑C for data transfer – used for charging and file transfer, but do not support video.
• USB‑C with DP Alt Mode (DisplayPort Alt Mode) – allows video output in resolutions up to 4K and 8K.
• USB‑C with Power Delivery (PD) – allows simultaneous video transmission and laptop charging.
• USB‑C USB 4 – the latest standard offering high bandwidth (up to 40 Gbps) and compatibility with Thunderbolt 3/4.

How to check whether a USB-C cable supports a monitor?

1. Check the manufacturer’s specifications – not every USB‑C cable supports DP Alt Mode.
2. Pay attention to the markings – cables that support video often have a DisplayPort or Thunderbolt symbol.
3. Test the connection – if the monitor doesn’t detect a signal, the cable may not support video transmission.

3. How does video transmission over USB‑C work?

The DisplayPort Alternate Mode (DP Alt Mode) function allows you to transmit video from a device to a monitor using a USB‑C cable. This solution eliminates the need for additional HDMI or DisplayPort cables.

What resolutions does USB-C support?

• USB-C 3.1 Gen 1 – up to 4K at 30 Hz
• USB‑C 3.1 Gen 2 – up to 4K at 60 Hz
• USB‑C USB 4 / Thunderbolt 3 and 4 – up to 8K at 60 Hz or 4K at 120 Hz

When choosing a USB-C cable for a 4K monitor, it’s worth making sure it meets the right technical requirements.

USB‑C doesn’t detect the monitor – what should you do?

If, after connecting the monitor via a USB‑C cable, there is no image, it’s worth checking:

1. Does the cable support DP Alt Mode – a regular USB-C charging cable does not transmit video.
2. Whether the USB-C port on the laptop supports video – not all USB-C ports allow video transmission.
3. Driver updates – missing compatible drivers can cause display issues.

4. Powering a laptop via USB‑C from a monitor

USB cable to a monitor – what for?

Some USB‑C monitors offer Power Delivery (PD), which means they can charge your laptop over the same cable that carries the video signal. This way, a single connection is enough for both work and charging at the same time.

How to connect a laptop to a monitor with USB-C power delivery?

1. Check compatibility – make sure both the monitor and the laptop support Power Delivery (PD).
2. Use the right cable – it must support both DP Alt Mode and Power Delivery.
3. Connect your devices – a single USB‑C cable is enough to power your laptop and transmit video.

5. Recommended cables

Summary of DEKO USB‑C cable capabilities in terms of video transmission and power delivery

By analyzing the specifications of DEKO USB‑C cables (both the 240W USB 4 and 100W USB 3.2 models), we can highlight the key features that matter for video transmission and power delivery from a monitor:

1. DEKO USB‑C USB 4 Cable (240W, 40 Gbps)

• Power supply: Supports Power Delivery (PD) up to 240W, which allows you to power laptops and other high‑power devices, provided that the monitor offers reverse power (Power Delivery).
• Video transmission: Supports video up to 8K at 60Hz or 4K at 120Hz, enabling high-quality image transmission between a laptop and a monitor (as long as both devices support DisplayPort Alternate Mode).
• Additional information: Offers data transfer up to 40 Gbps and features a built‑in e‑Mark Chip that ensures safe and efficient charging.

2. DEKO USB‑C USB 3.2 Cable (100W, 20 Gbps)

• Power supply: Supports Power Delivery (PD) up to 100W, allowing you to power devices when used with a monitor that supports PD.
• Video transmission: Supports 4K video at 60Hz, providing stable image quality but with a lower refresh rate compared to the USB 4 model.
• Additional information: Supports data transfer up to 20 Gbps and features e‑Mark technology for safe charging.

Key takeaways and caveats:

• Power Delivery (USB-C power output): To use the charging function, the monitor must support Power Delivery and provide power output over the USB‑C port.
• Alternate Mode (DisplayPort Alt Mode): Both the cable and the devices (laptop/monitor) must support the DP Alt Mode standard to enable video transmission.
• Compatibility: Before buying a cable, it’s worth checking whether your devices support the required USB‑C standards.
• Functionality depends on both devices: Even the best cable won’t guarantee operation if one element of the system (e.g. a monitor without PD) doesn’t meet the requirements.

DEKO USB-C cables offer fast charging and data transfer, including high‑resolution video. However, it’s crucial to make sure that your monitor supports Power Delivery and DisplayPort Alternate Mode in order to fully use their capabilities.

5. Summary

Which USB‑C cable for a monitor should you choose? It all depends on your needs. If you need a USB‑C cable for a 4K monitor, make sure it supports DP Alt Mode and provides sufficient bandwidth. If you also want to power your laptop, go for USB‑C with Power Delivery.

6. Sources

• MelGeek: Do all USB‑C cables support video? 
• Cable Time Tech: Debunking myths about video over USB-C
• BenQ: What is DisplayPort Alternate Mode?
• Super User: Does HDMI over USB‑C work without DP? 
• Reddit: Do all USB‑C cables support video?