HDMI 2.1 now allows 4K resolution up to 120 fps and for 8K, it supports up to 60Hz. HDMI 2.1 introduces additional High Dynamic Range formats, in particular, Dynamic HDR metadata were defined.
HDMI 2.1 is only needed if you want to use HDMI with 4K over 60Hz. This applies to consoles, as on PC you can get the same performance with DisplayPort 1.4, which is readily available.
Essentially, it all comes down to bandwidth: The current bandwidth capacity for HDMI 2.0 is 18Gbps, but HDMI 2.1 clocks in at a robust 48Gbps. This increase in bandwidth allows HDMI 2.1 to transfer way more information. In a nutshell, this means higher-resolution video and higher frame rates.
As we've established, HDMI 2.1 allows for higher resolutions at higher frame rates than before. With HDMI 2.0b, we could enjoy a maximum of 4K resolution at a maximum frame rate of 60Hz. With HDMI 2.1, we can get 4K at 120Hz, 8K at 60Hz, and right up to 10K resolution for industrial and commercial applications.
HDMI 2.1 supports refresh rates up to 8K at 60 Hz (Hertz) or 4K at 120 Hz, while HDMI 2.0 only supports 4K at 60 Hz. Refresh rate refers to how many times the display refreshes the image per second.
Buying HDMI 2.1 is worth it if you always want the best possible gaming or entertainment performance from your host devices. Getting an HDMI TV or monitor will guarantee that you can always enjoy 4K 120Hz with better HDR vibrancy and audio on platforms like the Series X and the PS5.
HDMI 2.0a – HDMI 2.0a offers all previous enhancements with different types of HDR. This enhanced cable allows for richer and more vibrant color. It is noticeable compared to the HDMI 1.4 and 2.0; however, you do not need this cable in order to support 4K.
HDMI 2.1 – the latest and greatest HDMI version – has the most support for 144Hz with the least compromise, allowing 1440p and 4K resolution at 144Hz; although anything higher than that and you'll need to use Display Stream Compression (DSC) or Chroma Subsampling. That said, 144Hz 4K TVs are few and far between.
New Supported Resolutions and Faster Refresh Rates
However, the main advantage of having HDMI 2.1 support on a 4k TV is that it can support 4k @ 120Hz content, which is what the newer gaming consoles output.
It is only necessary that the PS5 and the TV support HDMI 2.1. There is also a labeling problem here on the part of the technology. It would be easier for everyone if HDMI cables had the same name as the technology they support, starting from something as basic as that the standard has always been backward compatible.
Does Dynamic HDR require the new Ultra High Speed HDMI Cable? No, but it will be necessary to enable 4K120 and 8K60 video with HDR due to the high bandwidth required by these resolutions and refresh rates.
The latest HDMI 2.1a Specification delivers a powerful suite of gaming features that push the gaming experience to the highest level. The specification supports a resolution of 4K at 120Hz refresh rate, and even 144Hz for gaming TVs and monitors, and enables an immersive experience into the game worlds.
To be able to read the signal from either the PS5 or Xbox Series X/S, you need at least HDMI 2.0 connectivity (for 1080p at 120fps). Whereas, HDMI 2.1 is mandatory for 4K at 120fps.
On its own, HDMI 2.1 can only hit 120 Hz at 4K resolution, but by using VESA's Display Stream Compression (DSC), it should be able to reach 240 Hz, as explained by Tom's Hardware. Similarly, DisplayPort 1.4a runs 4K content at up to 120 Hz natively, but with DSC, a supporting 4K display could surpass that.
Low Input Lag
The delay is called input lag and spoils the gameplay and the continuity of the game. HDMI 2.1 comes with quick frame transport or QFT technology. It allows sources to deliver active video signals over the HDMI cable. As a result, gamers can experience a reduction in input lag.
A 2.1 HDMI cable can be as long as 50 feet or over. As a cable with a higher frame rate, the greater the distance the signal has to travel, the more quality loss there will be. For the best length and definition balance, we wouldn't recommend going over 20 feet.
HDMI 2.0 no longer exists, and devices should not claim compliance to v2. 0 as it is not referenced any more. The features of HDMI 2.0 are now a sub-set of 2.1. All the new capabilities and features associated with HDMI 2.1 are optional (this includes FRL, the higher bandwidths, VRR, ALLM and everything else)
So, keeping things as simple as possible, for a display to be able to receive a 4K 120Hz feed from a console it must have at least one HDMI capable of handling data rates of 32.08Gbps or more. That essentially means you are looking for TVs equipped with at least one HDMI port that supports the latest v2.
Only available on next-generation consoles and high-end gaming PCs, a 4K 120Hz HDMI cable solution for this kind of experience does exist, but you'll need the latest standard has to offer: HDMI 2.1.
To achieve 4K in 144 frames per second you need the best graphics cards money can buy, and we know finding one right now may prove tricky. As of this writing, you will definitely need an RTX 3080 Ti, RTX 3090, or RTX 3090 Ti on the NVIDIA side to ensure getting close to 4K 144Hz in demanding games.
To successfully stream 4K Ultra HD (4K) or High Dynamic Range (HDR) content, all devices connected via HDMI® to your compatible Roku® streaming player must support HDCP 2.2. This includes your TV, an audio/video receiver (AVR), and any other devices connected in between.
To achieve 8K@60Hz, 4K@144Hz, your monitor DisplayPort must be DisplayPort 1.4 version and support DSC. 8K resolution requires an 8K source, and an 8K display. Nintendo Switch not supported.
There really is no difference between a cable marketed as 4K and one that is not. But there is a label that does matter, and that is the speed rating. Speed will dictate the maximum bandwidth allowed by the cable.
Games in 4K 60Hz with HDR work perfectly on premium HDMI (HDMI 2.0), with room to spare. Note that the PS5/Xbox Series X|S ship with an ultra high speed HDMI cable (HDMI 2.1), so if you have that, use it. All HDMI versions are backward compatible.
HDMI cables 2.0 and 2.1 both deliver 4K High Dynamic Range (HDR) at higher refresh rates. However, that doesn't mean you would always get 4k HDR with these kinds of HDMI cables.