Why More and More Video Monitors Are Relying on USB-C

Apple's Pro Display XDR has a Thunderbolt 3/USB-C port. (Image: Apple)
Apple's Pro Display XDR has a Thunderbolt 3/USB-C port. (Image: Apple)

Just when it seemed that we’d all settled on one industry standard video input/output to make use of, along comes another one to complicate matters — you’ll now find USB-C competing with HDMI and other ports on modern computing and gaming monitors. Here we’ll explain why that’s happening, and what the pros and cons could end up being for consumers in the long run.

The first point to understand about the rise of USB-C monitors is that USB-C is, strictly speaking, just the spec of the physical interface of the port — it’s separate to the technology flowing through the cable to the port. Cables that you attach to USB-C ports will very often be using USB technology, but not always, and especially not when it comes to video and monitors (something USB doesn’t do very well).

USB-C ports can accept cables carrying a variety of audio and display protocols, including Thunderbolt, DisplayPort, and, yes, HDMI (though this is a lot less common than the first two). That’s one of the key reasons that a manufacturer might put a USB-C port on a monitor instead of an HDMI one: It’s much more versatile.

The BenQ PD3220U, with USB-C. (Image: BenQ)

There are other reasons: USB-C ports are smaller than HDMI ones, and so they take up less room (though this is more important on a laptop than a monitor). USB-C isn’t fussy about which way up you plug in the cable either, something that can’t be said for HDMI — a key consideration when you’re trying to reach behind a monitor to plug something in. USB-C cables work better over longer distances too.

As an added bonus, these video technologies with USB-C plugs at the end can often support some kind of USB transfer besides the video and audio. One way this could be applied is to feed touchscreen inputs back to a laptop from a connected monitor, for example. USB-C cables running from your monitor can also be used to charge devices and move data around, turning them into what are effectively USB-C hubs.

Of course all these benefits of the USB-C standard — versatility, compactness, ease-of-use — mean they’re now becoming very common indeed on laptops, especially the smaller and lighter ones. That in turn drives adoption on monitors, as manufacturers look to cater to the biggest slices of the market.

The Microsoft Surface Book 3, with USB-C. (Image: Microsoft)

Modern MacBooks offer do video output via Thunderbolt 3 over USB-C, while recent Surface hardware outputs DisplayPort 1.4 over USB-C. Keeping a full-sized HDMI port on a laptop just adds bulk.

While the rise of video-over-USB-C has offered us more choice, it’s also added a lot more confusion. A word of warning for when you’re actually choosing a USB-C monitor, or trying to choose between a USB-C and HDMI monitor: There are a confusing mix of combinations out there, so do due diligence on your research. Start with your source device (your laptop, probably), work out exactly how it outputs video, and go from there.

The main cause of the confusion is that not all USB-C ports are created the same: Just because a port is USB-C shaped, doesn’t really guarantee very much about it. Not every USB-C port can charge your devices and provide video output (or video input). It all depends on the choices made by the manufacturer.

The LG 24MD4KL-B, with USB-C. (Image: LG)

This extends to cables too, by the way — the same USB-C cable that charges your phone isn’t necessarily going to be able to take video from your laptop and put it up on a big screen. This should be made clear when you’re browsing through product listings, but it often isn’t, and so you need to be careful about what you buy.

In other words, just because your laptop comes with a USB-C port that offers video output doesn’t mean you can just directly connect it to a USB-C monitor. The Google Pixelbook is a case in point — you can use the USB-C connector to attach a second display, but you’ll need an adaptor somewhere along the line.

Look for references to “Alt Mode” when you’re browsing through laptops, cables, and monitors — this is what allows a USB-C connection to support more than USB (including Thunderbolt and DisplayPort audio and video transfer). If you’re lucky, you’ll be able to connect your computer to your monitor with one USB-C cable; if not, you’ll need an adaptor.

Apple's laptops now come with USB-C as standard. (Image: Apple)

HDMI has had its issues with versions and cables and implementations of course, but USB-C is trying hard to outdo it in terms of complexity: Check out this eye-watering (and very well researched) guide to the various Microsoft Surface USB-C video output options, for example, or this brilliantly in-depth and necessarily complicated explanation of how adding a hub affects the video quality you can get over USB-C.

Shopping frustrations and confusion aside, the HDMI connector standard isn’t going to disappear from monitors (or TVs) anytime soon — there are too many video consoles, Blu-ray players and cable boxes for that to happen. However, it’s likely to become even scarcer on laptops, as manufacturers will want to save space (while also knowing that USB-C dongles and hubs are widely available for users to turn to).

It’s a pity that a standard that initially offered a more straightforward, more convenient way of connecting and charging devices has become so complicated when it comes to getting video from one place to another, but we’re hoping that as older devices are phased out and USB-C becomes more common, more clarity will emerge. For now, just remember that the friendly USB-C port on a laptop or a monitor may have a variety of different roles, which you need to look at carefully.