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HDMI Features Explained: eARC, VRR, ALLM and What Actually Matters

2/2/2026 · HDMI · 7 min

HDMI Features Explained: eARC, VRR, ALLM and What Actually Matters

TL;DR

  • eARC enables high quality multichannel audio over HDMI and is essential for modern soundbars and AVR passthrough.
  • VRR reduces screen tearing by syncing GPU and display refresh, and is crucial for smooth gaming on TVs and monitors.
  • ALLM switches displays into low latency mode automatically, useful for consoles and game streaming devices.
  • HDMI version numbers are less important than supported features and bandwidth. Look for specific feature support like eARC, VRR and HDMI 2.1 bandwidth when buying.

What HDMI Actually Does

  • HDMI carries video, audio and control signals over a single cable.
  • Important features are often tied to the HDMI transmitter and receiver implementation rather than just the port label.

Bandwidth and Why It Matters

  • Higher bandwidth allows higher resolutions, higher refresh rates, and uncompressed HDR formats.
  • 4K at 120 Hz with HDR typically requires HDMI 2.1 level bandwidth or equivalent feature support.
  • If you only use 4K 60 Hz or 1440p 144 Hz, older HDMI 2.0 cables and ports can still be fine.

VRR and Gaming Smoothness

  • Variable Refresh Rate prevents tearing and reduces stutter by matching display refresh to frame output.
  • For competitive gaming, VRR on a monitor with low input lag is a major benefit.
  • On TVs, VRR helps with single player and variable FPS games but check the working range and minimum supported refresh.

eARC and Audio Systems

  • eARC carries high bitrate audio formats like Dolby Atmos TrueHD and lossless PCM to soundbars and AV receivers.
  • If you rely on a receiver or soundbar for audio, eARC removes the need for separate optical or ARC limitations.
  • eARC requires matching support on both TV and audio device and sometimes firmware updates.

ALLM and Low Latency Switching

  • Auto Low Latency Mode tells the display to enable its gaming picture profile automatically when a console or device requests it.
  • Useful for consoles and streaming boxes so you do not need to toggle modes manually.

Cables, Lengths, and Practical Tips

  • Premium High Speed HDMI cables and newer Ultra High Speed HDMI cables cover most needs.
  • For short runs under 3 meters, high quality passive cables work for 4K120 and eARC. For longer runs, consider active cables or fiber HDMI.
  • Avoid cheap no-name cables that do not declare their spec; they can cause flicker, no signal, or limited features.

Ports, Adapters and PC Compatibility

  • PC GPUs may label ports HDMI 2.1 but check driver and firmware support for features like VRR at 4K120.
  • Adapters can introduce limits. For example, passive adapters from DP to HDMI 2.1 rarely pass full 4K120 unless explicitly supported.

Which Features Should You Prioritize?

  • Home theater with external sound: eARC first, then HDR and bandwidth for video quality.
  • Console gaming: VRR and ALLM plus sufficient bandwidth for the console target (usually 4K60 or 4K120).
  • PC gaming: VRR and low input lag. If you want 4K at 120 Hz, confirm GPU and cable support.

Quick Buying Checklist

  • Confirm feature support on both devices, not just port labels.
  • Use Ultra High Speed HDMI cables for 4K120 and eARC when possible.
  • For long runs, prefer active HDMI cables or fiber solutions.
  • Check firmware updates if a feature is missing; vendors often add features post launch.

Bottom Line

HDMI features can be confusing, but focus on the functions you need. For sound systems pick eARC, for gaming pick VRR and ALLM, and for high frame rates pick cables and ports with the necessary bandwidth. Match devices and check firmware to get the most out of your setup.

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