Why does a single Gigabit network cable support a maximum of roughly 650,000 pixels on an LED display? In NovaStar, Brompton, and Colorlight LED control systems, each RJ45 output port on the sending card or video processor uses a 1 Gbps (Gigabit Ethernet) physical link. After accounting for Ethernet frame overhead, protocol synchronization headers, and a safety margin at 60 Hz frame rate and 8-bit color depth, the practical maximum pixel capacity per RJ45 port is 650,000 pixels (655,360 theoretical max).
1. The Bandwidth Formula Behind the 650,000-Pixel Limit
Every video frame transmitted over a Cat5e/Cat6 RJ45 cable must carry RGB color values for every pixel on that port’s cabinet chain, repeated 60 times per second:
- At 8-bit Color Depth (24 bits per pixel) & 60 Hz:
650,000 pixels × 24 bits × 60 Hz ≈ 936 Mbps, leaving ~64 Mbps for protocol overhead and timing safety within a 1,000 Mbps (1 Gbps) link. - At 10-bit Color Depth (HDR / 30–32 bits per pixel) & 60 Hz: Pixel capacity per port drops by ~25%–50% (typically 320,000–480,000 pixels per port depending on the controller series).
- At 120 Hz High Frame Rate (8-bit): Doubling the frame rate halves the available pixel load per port to roughly 325,000 pixels.
2. Practical Cabinet Loading Reference Table (60 Hz, 8-Bit)
When mapping refurbished rental LED cabinets in NovaLCT port mapping software, engineers typically leave a 10%–15% safety margin (targeting ≤550,000–600,000 pixels per port) to simplify rectangular row/column cascades:
| Pixel Pitch & Cabinet Size | Resolution per Cabinet | Pixels per Cabinet | Theoretical Max (650k Limit) | Recommended Safe Load per RJ45 Port |
|---|---|---|---|---|
| P3.91 (500×500 mm) | 128 × 128 px | 16,384 px | 39 cabinets (638,976 px) | 32–36 cabinets (8.0–9.0 m²) |
| P3.91 (500×1000 mm) | 128 × 256 px | 32,768 px | 19 cabinets (622,592 px) | 16–18 cabinets (8.0–9.0 m²) |
| P2.6 (500×500 mm) | 192 × 192 px | 36,864 px | 17 cabinets (626,688 px) | 14–16 cabinets (3.5–4.0 m²) |
| P2.5 (640×640 mm) | 256 × 256 px | 65,536 px | 9 cabinets (589,824 px) | 8–9 cabinets (3.2–3.6 m²) |
| P1.95 (500×500 mm) | 256 × 256 px | 65,536 px | 9 cabinets (589,824 px) | 8–9 cabinets (2.0–2.25 m²) |
3. Three Rules to Avoid Overloading Ports on Stage
- Verify the Bounding Rectangle in NovaLCT: Controllers allocate bandwidth based on the bounding rectangle of each port’s mapping area, not just the active cabinet count. Avoid jagged L-shaped cascades (read our NovaLCT Port Mapping Guide).
- Check Cable Length & Shielding: Use shielded Cat6 / etherCON cables under 85–100 metres; for FOH distances over 100 m, convert to single-mode optical fiber or 10G SFP links (RJ45 vs. Fiber & SFP Guide).
- Plan Redundant Backup Loops: For mission-critical live events, pair primary RJ45 ports with backup ports on your NovaStar video processor so a single unplugged etherCON jumper never causes a black screen.
Frequently Asked Questions
Q1: What happens if I daisy-chain more than 650,000 pixels on one RJ45 port?
Cabinets beyond the 650,000-pixel boundary will either remain blank, display truncated/garbled video, or trigger an overload warning in NovaLCT during screen connection configuration.
Q2: How many RJ45 ports do I need for a 100 m² P3.91 LED wall?
A 100 m² P3.91 wall has 400 cabinets (500×500 mm) totaling 6,553,600 pixels. At a safe load of 36 cabinets (589,824 pixels) per port, you need 12 primary RJ45 ports (e.g., two 6-port VX600 units or one 10-port VX1000 plus a secondary controller).
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