Understanding HDMI 2.1 and Why It Matters for Gaming

The arrival of PlayStation 5 and Xbox Series X brought console gaming into a new era, with capabilities that demand more from your television than ever before. At the heart of this evolution is HDMI 2.1—a specification that enables features once exclusive to high-end PC gaming. This guide explains what HDMI 2.1 offers and why it matters for your gaming experience.

HDMI 2.1 vs HDMI 2.0: The Key Differences

HDMI 2.1 represents a significant leap over its predecessor, HDMI 2.0. While both can handle 4K video, HDMI 2.1's dramatically increased bandwidth unlocks capabilities that simply weren't possible before.

What HDMI 2.1 Enables

• 4K resolution at 120 frames per second
• 8K resolution at 60 frames per second
• Variable Refresh Rate (VRR)
• Auto Low Latency Mode (ALLM)
• Enhanced Audio Return Channel (eARC)
• Quick Frame Transport (QFT)
• Quick Media Switching (QMS)

4K at 120Hz: The Headline Feature

The most discussed HDMI 2.1 capability is support for 4K resolution at 120 frames per second. For gamers, this combination delivers the sharpness of 4K with the smoothness of high frame rate gameplay—a combination previously requiring very expensive PC gaming monitors.

Why 120Hz Matters for Gaming

Frame rate directly impacts how smooth and responsive games feel. At 60Hz (the previous console standard), the display updates 60 times per second. At 120Hz, it updates twice as often, resulting in:

• Smoother motion: Fast-paced action looks more fluid
• Reduced input lag: Your inputs reach the screen faster
• Competitive advantage: In fast-paced games, you see enemy movements sooner
• Less motion blur: Fast-moving objects remain sharp

The difference is particularly noticeable in first-person shooters, racing games, and sports titles where quick reactions matter. Games like Call of Duty, Fortnite, and FIFA all support 120Hz modes on current-generation consoles.

4K@120Hz Game Support

Not all games support 4K at 120fps—many offer a choice between a quality mode (4K at 30/60fps) and a performance mode (often lower resolution at 120fps). However, a growing library of titles now offers true 4K@120Hz, including:

• Call of Duty: Modern Warfare series
• Fortnite
• Rocket League
• Destiny 2 (PvP modes)
• Halo Infinite (multiplayer)
• Rainbow Six Siege

Variable Refresh Rate (VRR)

Variable Refresh Rate is arguably the most impactful HDMI 2.1 feature for overall gaming experience. VRR allows the TV to synchronise its refresh rate with the console's frame output, eliminating screen tearing and reducing stutter.

How VRR Works

Traditional displays refresh at a fixed rate—typically 60Hz or 120Hz. When the console produces frames at a different rate, visual problems occur. If the console outputs 50 frames per second on a 60Hz display, frames display for inconsistent durations, causing stutter. If output exceeds the refresh rate, "screen tearing" occurs—visible horizontal lines where two different frames display simultaneously.

VRR solves this by dynamically matching the display's refresh rate to the console's frame output. If the game runs at 87fps, the TV refreshes at 87Hz. If it drops to 52fps during an intense scene, the TV follows. The result is smooth, tear-free gameplay regardless of frame rate fluctuations.

Auto Low Latency Mode (ALLM)

Auto Low Latency Mode automatically switches your TV to its game mode when a gaming source is detected. This might seem like a minor convenience feature, but it solves a real problem for many households.

Why ALLM Matters

Modern TVs apply extensive image processing—motion smoothing, noise reduction, contrast enhancement—that looks great for movies but introduces input lag problematic for gaming. Game Mode disables this processing, reducing the delay between pressing a button and seeing the result on screen.

Without ALLM, you need to manually switch picture modes whenever you move between watching content and gaming. ALLM handles this automatically—the TV detects when you launch a game and switches to Game Mode, then switches back when you return to streaming or broadcast content.

Enhanced Audio Return Channel (eARC)

While not exclusively a gaming feature, eARC significantly improves audio when using your TV as the hub for multiple devices connected to a soundbar or AV receiver.

eARC vs ARC

The original Audio Return Channel (ARC) could pass basic audio formats from TV apps to external audio systems. eARC expands this capability dramatically:

• Dolby TrueHD: Lossless audio from Blu-ray and streaming
• DTS-HD Master Audio: Full-quality DTS soundtracks
• Dolby Atmos: Object-based immersive audio
• Uncompressed 7.1: Full surround sound without compression

For gamers with home theatre systems, eARC ensures you hear game audio in its full quality, including 3D audio formats that provide spatial awareness of in-game sounds.

Checking Your TV's HDMI 2.1 Capabilities

Marketing around HDMI 2.1 can be confusing. Some TVs advertise "HDMI 2.1" while only supporting some features of the specification. Here's how to verify what your TV actually supports.

Key Specifications to Check

• 4K@120Hz: Confirm the TV can accept 4K at 120Hz input, not just 120Hz at lower resolutions
• VRR: Look for explicit VRR support, including the supported range (e.g., 48-120Hz)
• ALLM: Usually supported on any HDMI 2.1 port
• Number of HDMI 2.1 ports: Some TVs only have one or two full-bandwidth ports

Console Setup for HDMI 2.1

PlayStation 5 Setup

Navigate to Settings → Screen and Video → Video Output. Enable 120Hz output, VRR (if your TV supports it), and ensure HDR is enabled. Individual games may require enabling performance mode in their settings to access high frame rate options.

Xbox Series X Setup

Go to Settings → General → TV & Display Options. Set refresh rate to 120Hz, enable VRR and ALLM. Xbox also offers "Auto HDR" which adds HDR effects to older games—experiment to see if you prefer it enabled.

Is HDMI 2.1 Essential?

While HDMI 2.1 enhances the gaming experience, it's not strictly essential for enjoying current-generation consoles. Both PS5 and Xbox Series X work perfectly well via HDMI 2.0—you simply won't access 4K@120Hz or VRR features.

Consider HDMI 2.1 essential if you primarily play fast-paced competitive games and want every advantage. For casual gaming or primarily single-player experiences at 30-60fps, HDMI 2.0 remains perfectly adequate.