The Ultimate HDMI Guide: Cables, Versions, Bandwidth, and Compatibility Explained

HDMI is one of the most popular interfaces in consumer electronics, used in TVs, monitors, gaming consoles, laptops, graphics cards, media players, and home theaters. Thanks to HDMI, you can transmit both video and audio over a single cable-no extra wires or adapters needed. Despite its apparent simplicity, the HDMI standard includes a range of technical nuances: bandwidth, interface versions, operating modes, refresh rate support, audio features, and image formats. Understanding how HDMI works and the differences between its versions is crucial-not just for those shopping for a TV or graphics card, but for anyone who wants optimal picture quality, flawless HDR, and the full potential of 4K or 8K at the right frame rate. Choosing the right cable and ensuring device compatibility directly affects your viewing experience.

What Is HDMI and Why Do You Need It?

HDMI (High-Definition Multimedia Interface) is a universal digital interface for transmitting both video and audio via a single cable. It was designed to replace analog standards like VGA and component video, which are limited in quality and require separate audio connections.

The main goal of HDMI is to offer the simplest possible way to connect devices: TVs, projectors, monitors, game consoles, laptops, media players, and receivers. One cable can deliver:

• Video up to 4K and 8K resolution,
• Multichannel audio (Dolby Atmos, DTS:X),
• HDR metadata (HDR10, Dolby Vision, HLG),
• Refresh rates up to 120-144 Hz,
• Control information (CEC),
• Networking (with certain versions).

Unlike analog signals, HDMI transmits data digitally-eliminating noise and distortion, ensuring stable quality, and preserving image integrity even with longer cable runs (within technical limits).

Why Did HDMI Become the Number One Standard?

• Supports high resolutions and modern formats.
• Simplifies connections-video and audio in one cable.
• Universal: from TVs and consoles to PCs and projectors.
• Backward compatibility between device generations.
• Enhanced features-ARC, eARC, VRR, ALLM, HDR, CEC.

HDMI bridges the gap between home multimedia and the PC world, making it the standard for virtually all modern electronics.

How HDMI Works: The Physics of Signal Transmission

To understand why some cables support 4K 120 Hz and others do not, it's important to know how HDMI transmits data. Inside the cable, a high-speed digital system operates that is sensitive to conductor quality, cable length, and interference.

Digital Transmission via Differential Pairs

HDMI is based on TMDS (Transition Minimized Differential Signaling) technology. This technique uses three high-speed differential pairs for video data, a pair for the clock signal (in older versions), and additional conductors for audio, control, and auxiliary data. Differential transmission means each pair carries a direct and inverted signal, which the receiving device compares to:

• Reduce electromagnetic interference,
• Maintain stability at high speeds,
• Increase transmission range.

What HDMI Transmits Besides Video

A single HDMI cable can carry:

• Video data (RGB or YCbCr),
• Multichannel audio,
• HDR metadata,
• CEC commands (for device control),
• Synchronization channels,
• In newer versions-ARC/eARC audio return channel.

Compatibility depends on the features supported by the source device (e.g., PS5), the cable, and the receiving device (TV or monitor).

How the Video Stream Is Formed

The video signal is transmitted as a sequence of pixel data packed into TMDS frames, taking into account:

• Resolution,
• Color depth (8, 10, or 12 bits),
• Color space,
• Refresh rate,
• Auxiliary service data.

The higher the resolution and refresh rate, the more data needs to be transmitted, requiring higher bandwidth from both the HDMI version and the cable.

Why HDMI Is Sensitive to Cable Quality

TMDS signals operate at gigahertz frequencies, so cables must provide:

• Minimal signal loss,
• Consistent conductor quality,
• Proper shielding,
• Matched pair lengths (for synchronous signals).

Poor-quality, overly long, or non-standard cables can lead to:

• Artifacts,
• No picture,
• Non-functioning HDR,
• No 4K 120 Hz mode,
• Devices dropping to lower quality modes.

Key Takeaway: Bandwidth Determines Capabilities

The more data you need to transmit, the higher the interface's bandwidth must be.

This is why HDMI 1.4, 2.0, and 2.1 have vastly different capabilities-their bandwidth differs by several times. Next, we'll look at what impacts HDMI bandwidth and how it affects picture quality.

HDMI Bandwidth: What Determines Picture Quality?

Bandwidth is the main HDMI parameter that determines what kind of image (and with what characteristics) can be transmitted over the cable. Resolution, refresh rate, color depth, HDR, and audio formats-all depend on how much data the interface can handle.

What Affects HDMI Bandwidth?

Bandwidth is determined by several factors:

• Interface version (1.4, 2.0, 2.1),
• Signal encoding,
• Number of TMDS lines,
• Data rate per line,
• Compression mode (DSC), if used.

For the user, this boils down to a simple question: which HDMI version supports 4K 60 Hz or 4K 120 Hz?

Why Different Modes Require Different Bandwidths

1. Resolution: More pixels mean more data.
   • 1080p ≈ 2 million pixels
   • 4K ≈ 8 million pixels
   • 8K ≈ 33 million pixels

   Higher resolution requires more bandwidth.

2. Refresh Rate (60 Hz / 120 Hz / 144 Hz): The higher the refresh rate, the more frames per second are transmitted. For example, 4K 60 Hz requires about half the data of 4K 120 Hz.
3. Color Depth (8, 10, 12 bits): More bits per pixel increases the bandwidth load.
   • 8-bit: SDR
   • 10-bit: HDR10 / Dolby Vision
   • 12-bit: Premium HDR
4. Color Space (RGB / YCbCr):
   • RGB 4:4:4: Maximum quality, highest data rate.
   • YCbCr 4:2:2 / 4:2:0: Lower data rates due to reduced color information.

   Devices may automatically lower color format to stay within bandwidth limits.

Practical Examples That Matter

• HDMI 1.4 supports 4K only up to 30 Hz.
• HDMI 2.0 supports 4K 60 Hz, but not 4K 120 Hz.
• HDMI 2.1 supports 4K 120 Hz and 8K 60 Hz.
• PS5 / Xbox Series X use HDMI 2.1 for 4K 120 Hz and VRR.

Why Is HDMI 2.1 So Much Faster?

HDMI 2.1 increased bandwidth from 18 Gbps to 48 Gbps and switched to a new technology called FRL (Fixed Rate Link), which transmits data in packets rather than TMDS signals-reducing interference and enabling higher speeds.

Bottom line: Your device and cable's supported bandwidth directly determines the image quality you get. That's why differences between HDMI versions are so critical. Let's break down what each HDMI version can do.

HDMI Versions Compared: 1.4, 2.0, 2.1 and Their Capabilities

Each new HDMI version brings higher bandwidth and new features, enabling better picture and sound quality. Knowing the differences is essential for choosing the right cable, device, or TV-especially for 4K and 120 Hz content.

HDMI 1.4 - The Basic Standard for Full HD and Entry-Level 4K

Bandwidth: 10.2 Gbps

Main features:

• 1080p at 60 Hz
• 4K up to 30 Hz
• 3D video
• ARC (standard)
• 8-bit color
• CEC support

HDMI 1.4 works for older TVs and PCs but doesn't support 4K 60 Hz or HDR. Even if you connect a 4K monitor, it will max out at 30 Hz.

HDMI 2.0 - The Standard for 4K 60 Hz and HDR

Bandwidth: 18 Gbps

Features:

• 4K at 60 Hz
• HDR10 / HLG
• 10-bit color
• 4:4:4 at 8-bit or 4:2:2 at 10-bit
• Wider color gamut (BT.2020)

Improvements:

• Higher frame rates,
• Better color,
• HDR support.

However, HDMI 2.0 does not support 4K 120 Hz. Next-gen consoles are limited to 4K 60 Hz on this version.

HDMI 2.1 - The Modern Standard for 4K 120 Hz and 8K

Bandwidth: 48 Gbps (2.6x more than HDMI 2.0)

Features:

• 4K at 120 Hz
• 8K at 60 Hz
• Up to 144 Hz (on some monitors)
• 10- and 12-bit HDR
• Dolby Vision (device-dependent)
• VRR (Variable Refresh Rate)
• ALLM (Auto Low Latency Mode)
• eARC (enhanced audio return channel)
• FRL data protocol instead of TMDS

This is the only version that fully unlocks the potential of PS5, Xbox Series X, and the latest NVIDIA/AMD graphics cards.

Important: HDMI 2.1 ≠ Any Cable Labeled "2.1"

To achieve up to 48 Gbps speeds, you need a certified Ultra High Speed HDMI Cable. Non-certified "HDMI 2.1 cables" may not support high-speed modes-leading to issues with 4K 120 Hz, VRR, and HDR.

Version Names on Cables Are Now Banned-A Controversial Change

Current HDMI Licensing rules prohibit calling cables "HDMI 2.0" or "HDMI 2.1." Now, cables are classified as:

• High Speed - up to ~10 Gbps (FHD/entry-level 4K),
• Premium High Speed - up to 18 Gbps (4K 60 Hz),
• Ultra High Speed - up to 48 Gbps (4K 120 Hz, 8K).

So, always check the cable type, not just the version name.

HDMI Compatibility: Cables, Devices, Modes

Compatibility is one of HDMI's most important yet confusing aspects. While the standard aims for backward compatibility, actual performance depends on three key factors:

1. The HDMI version on the source,
2. The HDMI version on the receiving device,
3. The type and quality of the cable.

If any part of the chain doesn't support the desired mode, the entire system will default to a lower quality.

How HDMI Version Compatibility Works

HDMI operates on the principle that the weakest component determines the final operating mode.

Examples:

• Device HDMI 2.1 + cable 2.1 + TV HDMI 2.0 → Result: 4K 60 Hz
• Device HDMI 2.0 + cable 2.1 + TV HDMI 2.1 → 4K 60 Hz (limited by the source)
• Device HDMI 2.1 + cable 1.4 + TV 2.1 → Max 1080p 60 Hz

Versions don't "add up"-the lowest common denominator rules.

Compatibility by Resolution and Refresh Rate

To get, for example, 4K 120 Hz you need:

• A source with HDMI 2.1 (PS5, Xbox Series X, RTX 3000/4000, RX 6000/7000),
• Ultra High Speed cable (48 Gbps),
• TV or monitor with HDMI 2.1.

If any component is missing, you'll get 4K 60 Hz or lower.

Compatibility for HDR

HDR requires:

• HDMI 2.0 or higher,
• 10-bit color,
• YCbCr 4:2:2 or 4:2:0 at limited bandwidth.

If the cable is weak, HDR may:

• Turn off,
• Show artifacts,
• Drop to 8-bit mode with banding.

Audio Compatibility

Audio support also depends on the version:

• ARC (standard): Up to Dolby Digital / DTS.
• eARC: Uncompressed Dolby Atmos and DTS:X.

Even if your TV supports Atmos, if the receiver or soundbar doesn't, the format will automatically downgrade.

CEC and Device Control

CEC allows you to:

• Turn on the TV with your console's button,
• Control soundbar volume via the TV,
• Auto-switch inputs.

But CEC implementations vary by manufacturer, so:

• Some features may not work,
• Names differ (Anynet+, Bravia Sync, Simplink, etc.).

The Cable Also Affects Compatibility

Long or uncertified cables can:

• Drop 120 Hz support,
• Disable HDR,
• Reduce signal quality,
• Cause black screens and flickering.

Compatibility always involves all three elements: device → cable → display.

ARC and eARC: Audio Transmission Over HDMI

HDMI transmits not just video, but audio in both directions. ARC and eARC technologies enable your TV to send audio back to a soundbar or AV receiver, making home theater setup much simpler-one HDMI cable can replace several wires.

ARC - Audio Return Channel

ARC debuted with HDMI 1.4 and became the standard way to send sound from the TV to an external audio system. What ARC does:

• Outputs sound from TV apps (Netflix, YouTube, IPTV),
• Transmits basic formats:
  • Dolby Digital,
  • DTS (device-dependent),
• Uses the same HDMI cable-no separate audio cable needed.

ARC limitations:

• No uncompressed surround sound,
• No Dolby TrueHD, DTS-HD MA,
• No full Dolby Atmos (only compressed DD+ Atmos),
• Narrow bandwidth-about 1 Mbps.

ARC works for most mid-range soundbars but isn't sufficient for a true home theater.

eARC - Enhanced ARC

eARC arrived with HDMI 2.1, offering a high-speed dedicated audio channel. eARC can:

• Transmit uncompressed audio,
• Support:
  • Dolby TrueHD,
  • DTS-HD MA,
  • Dolby Atmos (full, uncompressed),
  • DTS:X,
• Work independently of CEC,
• Use a dedicated return channel with up to 37 Mbps bandwidth.

Advantages of eARC:

• Ideal for AV receivers and premium soundbars,
• Not dependent on the quirks of ARC or CEC sync,
• Delivers clear, lag-free, uncompressed sound.

ARC and eARC Compatibility

• TV with ARC + soundbar with eARC → ARC will be used (reduced features).
• TV with eARC + soundbar with ARC → ARC is used.
• Full eARC works only if both devices support it.

Note: eARC does not require HDMI 2.1 on all ports-some HDMI 2.0 models implement it if the manufacturer supports it.

Do You Need a Special Cable for eARC?

Yes: eARC is guaranteed to work with Ultra High Speed HDMI Cables. Regular High Speed HDMI Cables may work, but can be unstable with uncompressed formats.

How to Choose an HDMI Cable for 4K, 8K, 60/120 Hz, and PS5/Xbox

The right HDMI cable isn't just an accessory-it's essential for getting 4K 120 Hz, HDR, VRR, Dolby Vision, and even proper ARC/eARC audio. Resolution and refresh rate depend on the entire chain: source → cable → display. And the cable is often the weakest link.

Understanding HDMI cable classes and their true bandwidth is the key to making the right choice.

HDMI Cable Classes: What Do They Mean?

1. High Speed HDMI Cable
   • Bandwidth: up to ~10 Gbps
   • Suitable for:
     • 1080p 60 Hz
     • 1440p 60 Hz
     • Entry-level 4K 30 Hz (no HDR)
   • Not suitable for:
     • 4K 60 Hz HDR
     • 4K 120 Hz
     • 8K
     • PS5 / Xbox Series X
2. Premium High Speed HDMI Cable
   • Bandwidth: up to 18 Gbps
   • Suitable for:
     • 4K 60 Hz SDR/HDR
     • 4K 60 Hz Dolby Vision
     • eARC (sometimes unstable)
   • Not suitable for:
     • 4K 120 Hz
     • 8K

   This is the optimal choice for TVs and consoles before the HDMI 2.1 era.

3. Ultra High Speed HDMI Cable
   • Bandwidth: up to 48 Gbps
   • Suitable for:
     • 4K 120 Hz
     • 4K 144 Hz (on some monitors)
     • 8K 60 Hz
     • HDR10 / Dolby Vision
     • VRR, ALLM, QFT
     • eARC without limitations
     • PS5 and Xbox Series X / Series S
     • RTX 3000/4000, RX 6000/7000

   This is the only cable type that reliably supports all HDMI 2.1 modes.

Which Cable Do You Need for Your Setup?

• For PS5 / Xbox Series X: Only Ultra High Speed HDMI Cable (for 4K 120 Hz, VRR, HDR)
• For 4K 60 Hz HDR: Premium High Speed is enough (any TV with HDMI 2.0, media players, PC)
• For 8K: Only Ultra High Speed
• For eARC and Dolby Atmos: Preferably Ultra High Speed, though Premium High Speed may sometimes work-expect possible issues
• For 144 Hz 4K PC monitor: You need Ultra High Speed, or the refresh rate will be limited

Why Cable Length Matters

The longer the HDMI cable, the higher the risk of:

• Artifacts,
• Flickering,
• Disconnections,
• Loss of HDR/4K/120 Hz.

Recommended lengths:

• Up to 3 meters: almost any good-quality cable will work reliably
• 5 meters: higher risk-use only quality Premium High Speed
• 7+ meters: only optical HDMI cables, otherwise 4K 120 Hz is nearly impossible without errors

How to Tell If a Cable Is Truly Ultra High Speed

Genuine certified cables have:

• A QR code on the packaging,
• The label "Ultra High Speed HDMI Cable,"
• A certification logo with a number.

If a cable is simply labeled "2.1," it means nothing-brands often mark 18 Gbps cables as "HDMI 2.1."

Choosing the right cable ensures that even the most advanced devices work at their maximum quality without limitations or unexpected issues.

Why HDMI Might Not Work: Causes and Solutions

HDMI is supposed to be plug-and-play, but in practice, users often face black screens, flickering, missing sound, or lack of 4K/120 Hz. The cause is almost always mode incompatibility, the wrong cable, or incorrect settings. Here are the most common scenarios:

1. HDMI Version or Mode Incompatibility

   If any part of the chain (source → cable → display) doesn't support the desired mode, the picture:

   • Won't display,
   • Appears at low quality,
   • Cuts out when trying to enable HDR/120 Hz.

   For example:

   • TV HDMI 2.0 + Ultra High Speed cable + PS5 → max 4K 60 Hz
   • High Speed cable + TV HDMI 2.1 → max 1080p / 1440p

   Solution: Check the version and bandwidth support of each component.

2. Poor-Quality or Overly Long Cable

   Even if a cable is labeled "4K," "2.1," or "8K," its real bandwidth may be lower.

   Signs of a bad cable:

   • Flickering,
   • Disappearing image,
   • HDR disables,
   • Frame rate drops to 30 Hz,
   • Green or purple artifacts.

   Solution:

   • Use certified Premium High Speed (for 4K 60 Hz),
   • Or Ultra High Speed (for 4K 120 Hz / 8K),
   • Keep length under 2-3 meters,
   • For long runs, use optical HDMI.
3. Incorrect TV or Monitor Settings

   Some TVs default to a limited compatibility mode (HDMI 1.4/2.0), even if the port supports HDMI 2.1.

   Examples:

   • On LG: Enable "HDMI Ultra HD Deep Color"
   • On Samsung: Enable "Input Signal Plus"
   • On Sony: Enable "Enhanced Format"

   Without this, 4K 120 Hz and HDR won't activate.

   Solution: Turn on enhanced HDMI mode in the input settings.

4. Incorrect Graphics Card or Console Settings

   If your PC or console is set to an unsupported format:

   • RGB 4:4:4 12-bit (too heavy),
   • 4K 120 Hz on HDMI 2.0,
   • Non-standard refresh rates,

   Artifacts or a black screen may occur.

   Solution:

   • Switch color format (YCbCr 4:2:2 / 4:2:0),
   • Lower color depth to 10/8 bits,
   • Check VRR/ALLM modes.
5. ARC/eARC Audio Issues

   If there's no sound over HDMI, it's usually due to:

   • ARC/eARC mismatch,
   • Unsupported audio format,
   • Poor cable,
   • CEC disabled.

   For example: a TV with ARC can't send Dolby TrueHD or DTS:X-sound will be missing or downgraded.

   Solution:

   • Use eARC for uncompressed Atmos audio,
   • Check that CEC/ARC/eARC is enabled,
   • Switch to Ultra High Speed cable.
6. HDCP Issues

   HDCP is a content protection system. If your TV or cable doesn't support the right version:

   • You'll see protection errors,
   • Streaming services refuse to play video,
   • The image disappears.

   Solution: Use modern cables and devices (HDCP 2.2 for 4K).

7. Physical Port or Cable Problems

   Sometimes the issue is simple:

   • Loose connector,
   • Cable not fully inserted,
   • Damaged contacts,
   • Dirty ports.

   Solution:

   • Reconnect cables,
   • Check connectors,
   • Try a different cable or port.

Bottom line: In most cases, HDMI "not working" isn't a hardware failure. 90% of problems come from the wrong cable, incorrect settings, version mismatches, or trying to use a mode unsupported by one of the devices. Choosing the right cable and proper HDMI port configuration solves nearly all issues in minutes.

Conclusion

HDMI has become the universal standard for audio and video transmission thanks to its plug-and-play simplicity and extensive capabilities. Yet behind its familiar connector lies a complex high-speed data system, where everything-from interface version to cable quality-impacts your final image and sound. Understanding how HDMI works helps you avoid issues with 4K and 8K playback, choose the right cable for your gaming console, properly set up your TV or monitor, and get the most from your modern devices.

The main differences between HDMI 1.4, 2.0, and 2.1 are bandwidth and feature set. HDMI 2.1 unlocks 4K 120 Hz, VRR, ALLM, eARC, and other next-gen features-but these modes require full compatibility across source, cable, and display. ARC and eARC simplify audio system connections, while the right cable ensures stable picture and HDR functionality.

By understanding interface principles, version differences, and equipment requirements, you can easily set up your home theater, gaming rig, or workstation to make HDMI work at its best-without artifacts, quality limitations, or unexpected technical issues.