You don't need an HDMI 2.1 connection for 120hz gaming, and many PC players have been able to experience 120fps for some time with an HDMI 2.0 connection. An HDMI 2.1 connection essentially allows for 120fps at 4K, or 8K at 60fps, while an HDMI 2.0 connection can allow for 120fps, but at either 1080p or 1440p.
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.
Any HDMI cable is going to pass a signal that the 4K/120Hz TV can display. It really matters what the source content is as to what you're trying to pass to the TV. Content coming out of your cable box, streaming device, etc is likely not to be 4K 120Hz in the first place.
The biggest thing with HDMI 2.1 is the exponential growth in bandwidth compared to HDMI 2.0, which has been most associated with 4K 60Hz. However, HDMI 2.0 also does have the ability to execute 4K 120Hz.
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.
Thus, HDMI 2.0 is strong enough to produce 4k video at 50 and 60 FPS respectively. But it's 4k@120Hz or 4k@144Hz that actually pumps energy in the video. Unfortunately, you can get this with HDMI 2.0. Yet, there is a quick trick that may stop you from undue spending to upgrade to HDMI 2.1.
HDMI 2.0 has a bandwidth capacity of 18 Gbps (gigabits per second). HDMI 2.1 takes the number up to 48 Gbps, which means that HDMI 2.1 does not have to compress that much of the data and preserve a better data quality during the transmission process.
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.
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.
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.
The higher the number, the smoother the screen will appear to the human eye. This means that a 120Hz display – which updates itself 120 times a second – will look noticeable slicker and more natural than your average 60Hz screen which only updates itself 60 times a second.
The “4k HDMI” label is mostly marketing, so it doesn't mean a specific feature that will improve image quality. But if you have any cables past the HDMI 1.4 version, then they will be moving the same 4k image across the cable regardless of any marketing.
There is no Such Thing as a 120Hz / 240Hz HDMI Cable
The truth is, these higher refresh rates are being handled by the display, not by the source.
Do all 4K TVs have a 120Hz refresh rate? As said earlier, the refresh rate of a TV may be more and less depending on many other factors, from resolution, the number of pixels, and most importantly, the frame rate. Not all 4K TVs have a refresh rate of 120Hz. Most of the older models 4K TV have a refresh rate of 60Hz.
All in all, if you have or plan on getting a gaming PC or a console that supports 120Hz, you should definitely get a 120Hz TV as it makes for a more responsive and immersive gaming experience. Keep in mind that to get the most out of 120Hz, you should also be able to maintain around 120FPS (Frames Per Second).
To enable 4K gaming at 120 Hz, press the Xbox button to open the guide, and then select Profile & system > Settings > General > TV & display options. Make sure that your Resolution is set to 4K UHD and your Refresh rate is set to 120 Hz.
Overview of HDMI 2.0
Released in September 2013, the specification includes support of increased bandwidth up to 18 Gbps, resolutions up to 4K @ 60 Hz, simultaneous delivery of two video streams and up to four audio streams, 32 channels of audio, as well as other key enhancements.
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.
You don't absolutely need HDMI 2.1 to reach 120Hz or even 144Hz refresh rates, but it is important for supporting both high refresh rates and high resolution at the same time.
HDMI 2.0 can easily support a refresh rate of 4K@60 Hz (Hertz). But HDMI 2.1 is stronger. It holds up to 8k@60 Hz or 4k@120 Hz. But you can only achieve these results only by using a best HDMI 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.
The connectors are the same size and shape, and HDMI 2.1 is backward compatible with your current 2.0 or earlier equipment. Even if you haven't upgraded your audio/video equipment or computers to HDMI 2.1, your cables will work with your existing devices, though without most of HDMI 2.1's advanced features.