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.
So, What Should I Do? 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. So, it's likely adding HDMI 2.1 cables and expense to your setup is not something you need to worry about now.
HDMI 2.1 can support higher frame rates for smoother video, but it also allows variable frame rates.
HDMI 2.0 vs 2.1 – Features
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.
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 Apple TV 4K, you need an HDMI 2.0 or later compatible cable. To access all of the features that your Apple TV has to offer, use an HDMI 2.1 cable.
For 144Hz at 1440p, you will need at least HDMI 2.0 or DisplayPort 1.2 while for 4K 144Hz you are going to need HDMI 2.1 or alternatively, DisplayPort 1.4 with DSC 1.2.
Variable refresh rate
As we mentioned in the section on resolution, HDMI 2.1 can support higher frame rates for smoother video. But just as importantly from a gaming perspective, it allows for variable frame rates. Modern PC and console games do not use a single frame rate throughout the game.
That said, HDMI is and has always been fully backward compatible. It's perfectly fine to use a TV equipped with HDMI 2.1 with an older HDMI cable. It's also perfectly fine to use a next-generation console with a TV that has HDMI 2.0. They will work, but won't be capable of outputting in 4K at 120Hz or higher.
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.
You're in luck — all you need is a single HDMI cable to connect your TV and soundbar enabled with Dolby Atmos (HDMI 2.0 for ARC should do the trick while HDMI 2.1 is necessary for eARC setups). This is the simplest option and will send audio directly from your TV to your soundbar.
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. HDMI 2.0 connections also allow for 4K at 60hz, which has been enjoyed for some time thanks to consoles like the PS4 Pro and Xbox One X.
No problem, it is about the same bandwidth requirements as 4k at 60Hz (and at 14Gbit/s for 1920*1080P@240Hz it is below the 14.4Gbit/s limit of HDMI 2.0 standard) so it will work just fine.
HDMI 2.1a Dynamic HDR
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.
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.
Can a very expensive HDMI cable show a better picture and sound quality than a cheaper one? The quick answer is no. An HDMI cable, regardless of the materials used, can either transmit a signal or not – there's no in-between. An expensive HDMI doesn't produce richer colors or crisper sound than cheaper versions.
You can simply check the back of the TV to see what's written above the HDMI inputs. Although some inputs won't specifically say 'HDMI 2.1', it may show the maximum refresh rate at 4k; an HDMI 2.0 input shows '4k @ 60Hz', while an HDMI 2.1 input shows '4k @ 120Hz' and may also have an eARC label.
However, it's worth noting that HDMI 2.1 cables are backward compatible with their predecessor. Even if your current setup mostly offers HDMI 2.0 ports, using an HDMI 2.1 cable will give you a satisfactory experience.
HDMI 2.1 monitors are a bit of a game-changer, especially for PS5 and Xbox Series X players, as they can allow for faster refresh rates and smoother gaming. Of course, if you have any one of the best gaming PCs, an HDMI 2.1 display can also be used for the same resolution and framerate.
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.
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.
Getting 4k With HDMI 2.0 Is Not As Simple As You May Think
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.
The Apple TV 4k works with TVs all the way down to 480p video resolution. This also applies to people that have 4k TVs without HDR capability - the Apple TV will stream the SDR 4k content instead of the higher-bandwidth HDR 4k content. A: Yes it does. Currently streaming services like iTunes, Netflix are supported.
18Gbps HDMI can support Dolby Vision up to 4K/60. HDMI 2.1 will unlock higher frame rates and variable refresh rate gaming.
Should I upgrade? If you're in the market for a new TV and want the best of the best, we recommend buying one with at least one HDMI 2.1 port, especially if you're into gaming.