HDMI 2.1 was supposed to herald a new age of widespread high-bandwidth, low-latency, and lossless media consumption. As far as monitors are concerned, however, that promise hasn't really panned out. Having an HDMI port on your monitor with the HDMI 2.1 spec doesn't automatically guarantee access to the entire feature set of the standard. It all depends on which particular features the manufacturer chooses to implement on your model. Add to that the confusion among consumers regarding which HDMI cable to buy, and it's all a mess that has lasted for far too long.

Enhanced Audio Return Channel (eARC)

Guaranteed lossless audio? Think again

If you have a TV purchased after 2009, you've probably heard of HDMI ARC. This feature became a mainstay of the HDMI standard in the late 2010s, allowing your TV (or monitor) to send audio to a compatible speaker or soundbar via the HDMI cable, negating the need for additional cables. eARC is an extension of ARC that allows for greater bandwidth audio connections via the HDMI link, and was implemented as part of the HDMI 2.1 standard.

What this means is that an HDMI 2.1 port on your monitor should allow you to stream content with lossless audio formats, such as Dolby Atmos and DTS:X to compatible audio systems. However, your monitor's manufacturer isn't mandated to offer support for these formats, so the on-ground support is always up in the air. Even if your fancy new monitor and soundbar have HDMI 2.1 ports, it doesn't guarantee support for all the lossless audio formats available.

Quick Frame Transport (QFT)

Not so quick in implementation

Another feature part of the HDMI 2.1 standard, Quick Frame Transport, or QFT, is even more elusive. Ideally, every device with an HDMI 2.1 port should be able to utilize QFT to speed up the transmission of each frame from the source to the destination, reducing the overall input lag. QFT does this by utilizing the higher bandwidth and speed of the HDMI 2.1 standard to transmit frames from a PC or console to the display as soon as they're ready.

In reality, however, there are only a handful of displays that support QFT, despite supporting HDMI 2.1. Even the PlayStation 5 and Xbox Series X don't support the feature yet. It might be possible to enable support in the future with a software update, but there are no signs of that happening anytime soon. Many Nvidia and AMD GPUs are known to support QFT, but it isn't really marketed. The thing is, latency on modern gaming devices and displays is already pretty low, hence the urgency for widespread QFT isn't that pressing. With time, we might see the feature make its way to more devices.

Quick Media Switching (QMS)

Get rid of the annoying blank screen

You might not have heard of Quick Media Switching (neither did I), but it's one of the most useful features of the HDMI 2.1 standard. In a nutshell, it prevents the familiar blank screen that appears when switching between signals with different refresh rates. It adjusts the refresh rate of the display in real time, similar to how VRR operates (more on that later). QMS only eliminates the delay associated with switching the refresh rate, not those linked to changing the resolution or HDR format, meaning the last two parameters should stay constant.

Even if your monitor supports the feature as part of the HDMI 2.1 standard, you might not find a compatible source device. As far as I can tell, only the Apple TV 4K (3rd gen) and a few LG and Samsung TVs support it. QMS can help eliminate the 2–3 second delay when switching from high-refresh-rate to low-refresh-rate content and vice versa — having more support for it would be appreciated.

Auto Low Latency Mode (ALLM)

It's one I can do without

Auto Low Latency Mode, or ALLM, is a feature most commonly seen on modern TVs, and is used to optimize the display for gaming. All it does is automatically switch the TV into its lowest latency mode, usually labeled "Game Mode", thereby reducing the overall latency for the best results. The Game Mode disables all the extra processing on the TV that's always running in the background, and ALLM removes the need for the user to manually switch to this mode when launching a game.

Most monitors usually don't feature ALLM, since they already have low input lag as compared to TVs. Some gaming monitors, especially those launched in 2023 and later, do feature ALLM, but the overall benefits might be slim. Just like other features of the HDMI 2.1 spec, ALLM isn't mandatory to be implemented by the manufacturers, leaving a question mark over the compatibility of your particular monitor.

HDMI-Variable Refresh Rate (HDMI-VRR)

It's good to have broader support

While you might be used to proprietary VRR standards like FreeSync or G-Sync on your gaming monitor, the broader standard known as HDMI-VRR isn't as prevalent. Introduced as part of HDMI 2.1, it was intended to bring widespread VRR support to all devices using HDMI 2.1. Consoles like the PS5 and Xbox Series X, and many TVs support HDMI-VRR, but monitors usually implement FreeSync or G-Sync to compensate for screen tearing and stuttering.

HDMI-VRR might not be supported on your monitor even if it has an HDMI 2.1 port. While the VRR standard you use on your monitor doesn't make much difference functionally, having HDMI-VRR can improve support when you want to connect to consoles, and not just your PC.

Dynamic HDR

You might be stuck on static HDR

There's HDR, and then there's HDR. Static HDR via formats like HDR10 is inferior to dynamic HDR formats like Dolby Vision and HDR10+. Dynamic HDR makes use of dynamic metadata to inform the display on a per-scene or even per-frame basis, which leads to more granular control over the HDR image quality. In contrast, static HDR uses metadata that remains unchanged throughout the content.

Dynamic HDR existed before HDMI 2.1 became a thing, but the new standard made the feature a standard part of the specification. However, not all HDMI 2.1 monitors implement dynamic HDR support, even though your source device (PC or console) and the cable itself might support it. This can lead to a subpar HDR experience than what should be possible in the HDMI 2.1 ecosystem.

HDMI 2.1 in name only

Many modern gaming monitors have the once-elusive HDMI 2.1 port, but that doesn't mean you'll get all the features of the spec. One or more aspects of the HDMI 2.1 standard are likely to be absent from your monitor because your manufacturer deemed it unnecessary or too expensive. Although your gaming experience, at least on PC, might remain largely unaffected, you'll probably miss the broader support that's the hallmark of HDMI 2.1.