NVIDIA has innovatively adopted copper cable backplane technology in the GB200 series, achieving direct GPU-to-switch chip connections through NVLink Switch. Each GB200 super chip consists of two Blackwell GPUs and one Grace CPU, connected via NVLink C2C protocol (with a unidirectional bandwidth of 450GB/s). A single NVL72 cabinet can house 72 GPUs, forming a “super GPU” architecture.
In the interconnection architecture, copper cables are mainly used for backplane connectors to the cable backplane, switch chip jumpers, and other scenarios. For example, the NVL72 system uses 5184 copper cables to directly connect 72 GPUs, achieving 900GB/s of unidirectional bandwidth through custom high-density connectors, such as Amphenol Paladin HD 224G.
I. Introduction about Nvidia GPU Copper Cable Interconnect
With the explosive growth in AI computational power demand, high-speed interconnections between GPU clusters have become a key bottleneck limiting computing density. NVIDIA has built an all-scenario solution from single cabinets to cross-cluster interconnects using copper cable interconnect technology, achieving a breakthrough balance between cost, power consumption, and performance. This article will systematically analyze the core value of NVIDIA’s copper cable interconnect technology from the perspectives of technical principles, product applications, and industry comparisons.
II. Key Technology Analysis
✅ Architecture Evolution and Core Technological Breakthroughs
NVLink Copper Cable Technology: In the GB200 system, 72 Blackwell GPUs are fully interconnected via 5000 NVLink copper cables, with a total length exceeding 2 miles. Each copper cable uses 224G PAM4 signal modulation, with a single-channel rate of 224Gbps, supporting bidirectional 1.8TB/s bandwidth, which is 14 times faster than PCIe 5.0.
Signal Integrity Design: Signal regeneration is achieved through Retimer chips (such as AEC solutions) to address the attenuation issue of copper cables at high speeds. For instance, AEC transmission can reach 5-6 meters at 112G rates, whereas DAC can only support 1 meter.
Connector Innovation: Amphenol Paladin HD 224G/s connectors are used, with a single connector integrating 72 differential pairs, supporting high-density deployment in blade servers.
✅ Copper Cable Technology Classification and Scenario Adaptation
DAC (Direct Attached Copper Cable): Passive design, costing only 1/6 of optical modules, power consumption <0.1W, suitable for ultra-short-range connections within 3 meters (e.g., interconnection within NVL72 cabinets).
ACC (Active Copper Cable): Integrates Redriver chips, extending transmission distance to 1.5 meters at 112G rates, with a 30%-40% cost increase, used for inter-tray connections.
AEC (Active Enhanced Copper Cable): Uses Retimer chips for signal reconstruction, achieving transmission distances of 5-6 meters at 112G rates, with a cost of 30% of optical modules, making it the core solution for medium to long-range interconnections.
✅ System-Level Optimization
Power Consumption Control: Copper cables do not require optical-electrical conversion, saving 20kW of power consumption in a single NVL72 cabinet compared to optical module solutions.
Heat Dissipation Design: Copper cables have low heat density and support high-density deployment of liquid cooling systems. For example, the computational power of a single GB200 cabinet reaches 1EFLOPS.
III. Core Performance Indicators Comparison
| Metric | NVIDIA Copper Cable | Optical Module | AMD Infinity-Fabric |
|---|---|---|---|
| Bandwidth (per channel) | 224Gbps (PAM4) | 112Gbps (NRZ) | 92GB/s (CPU-GPU Interconnect) |
| Transmission Distance | 7m (AEC) | 10km (Single-mode Fiber) | Motherboard-level Interconnect |
| Power (per module) | <0.1W (DAC) | 3W (800G) | Not disclosed |
| Cost (per module) | $260 (800G DAC) | $450 (800G) | Not disclosed |
| Latency | ~10ns | ~50ns | Not disclosed |
IV. Full-Spectrum Product Applications
✅ GB200 and NVL72 System
Architectural Innovation: Adopting a blade-style design, 72 GPUs are fully interconnected via NVLink copper cables, with a single cabinet achieving 1EFLOPS of computational power, a 4x improvement over previous generations.
Cost Advantage: The total cost of copper cables for a single cabinet is about $220,000, only 1/6 of the cost of optical module solutions.
✅ Ruby Servers and DGX Series
Interconnection Density Enhancement: Ruby servers use AEC copper cables, increasing the number of GPUs per cabinet to 144, with a 30% improvement in bandwidth utilization.
Cross-Cluster Expansion: The GB300 plan will use 1.6T optical modules and copper cables in coordination, achieving 1.6Tbps inter-cabinet interconnection bandwidth.
✅ Industry Adaptability
Training Scenarios: The NVLink copper cables of the H100 support 900GB/s bandwidth, increasing the speed of training GPT-4 by 7 times compared to the PCIe version.
Inference Scenarios: The PCIe copper cable solution for the A100 is more cost-effective, suitable for small to medium-scale inference clusters.
V. Industry Comparison and Trend Outlook
✅ Competitive Landscape with Optical Modules
Short-Range Scenarios: Copper cables dominate in-cabinet interconnections due to advantages in cost (1/6) and power consumption (1/30), with penetration expected to exceed 80% by 2025.
Long-Range Scenarios: Optical modules remain irreplaceable for inter-data-center connections, but copper cables, through AEC technology, are penetrating the 5-7 meter range.
✅ Differences with AMD Infinity Fabric
Technical Path: AMD’s Infinity Fabric focuses on CPU-GPU memory consistency interconnects with a bandwidth of 92GB/s, while NVIDIA’s copper cables focus on high-speed GPU-to-GPU communication.
Application Scenarios: AMD’s solution is suitable for heterogeneous computing, while NVIDIA’s copper cables lead in pure GPU clusters in terms of performance.
✅ Future Technology Evolution
Copper Cable Upgrade: 224G single-channel copper cables are already in the sample phase, expected to support 1.6T speeds by 2026, with transmission distances exceeding 10 meters.
Optical-Copper Collaboration: NVIDIA plans to adopt a “short-range copper cable + long-range CPO” architecture in the GB300, further optimizing cost and performance.
Silicon Photonics Integration: Jensen Huang confirmed continued use of copper cable technology, while collaborating with TSMC on silicon photonics, aiming for commercialization by 2030.
VI. Conclusion
NVIDIA’s copper cable interconnect technology, through signal modulation optimization, chip-level enhancements, and system-level collaboration, has established the performance benchmark for short-range interconnects. Its core advantages lie in the balance between cost, power consumption, and performance, making it a key support for AI computing infrastructure.
In the future, with the maturation of 224G copper cable technology and the integration of silicon photonics, NVIDIA will further strengthen its leadership in the GPU interconnect field, driving AI computing power into a new period of explosive growth.
Source: Internet
Related:
- Why Gold Is Plated on Wafers After Nickel Layer
- PCB Layout Tips to Improve Rectifier Heat Dissipation
- Step-by-Step Guide to Wafer Plating Rate Formula
- Key Differences: Wafer Plating, Electroforming, Electrolysis
Disclaimer:
- This channel does not make any representations or warranties regarding the availability, accuracy, timeliness, effectiveness, or completeness of any information posted. It hereby disclaims any liability or consequences arising from the use of the information.
- This channel is non-commercial and non-profit. The re-posted content does not signify endorsement of its views or responsibility for its authenticity. It does not intend to constitute any other guidance. This channel is not liable for any inaccuracies or errors in the re-posted or published information, directly or indirectly.
- Some data, materials, text, images, etc., used in this channel are sourced from the internet, and all reposts are duly credited to their sources. If you discover any work that infringes on your intellectual property rights or personal legal interests, please contact us, and we will promptly modify or remove it.
