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GB200 NVL72 vs MI355X: Why Systems Win MoE Inference

·528 words·3 mins
NVIDIA AMD GPU Benchmarks Data Center
Table of Contents

Recent Mixture-of-Experts (MoE) inference benchmarks have made one point unmistakably clear: in 2026, systems outperform silicon. NVIDIA’s Blackwell-based GB200 NVL72 rack-scale platform has demonstrated up to 28× higher throughput than AMD’s Instinct MI355X in high-concurrency MoE workloads such as DeepSeek-R1.

This gap is not explained by raw FLOPs. It is explained by architecture above the GPU.

🧠 Why MoE Is a System Problem
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MoE models behave fundamentally differently from dense transformers. Each generated token dynamically selects a subset of experts, which creates a communication-heavy execution pattern.

Key characteristics of MoE inference:

  • Sparse but dynamic parameter access: Active weights change per token.
  • Frequent cross-GPU hops: Tokens must move between experts.
  • Synchronization sensitivity: Compute stalls if interconnect latency is high.

In practice, this means MoE performance is dominated by interconnect bandwidth, latency, and memory locality, not peak accelerator specs.

🏗️ GB200 NVL72: The System-on-a-Rack Model
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The GB200 NVL72 is not a cluster of GPUs. It is designed and scheduled as one coherent system.

Architectural advantages
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  • NVLink Switch System
    Seventy-two Blackwell GPUs are connected through a fully non-blocking NVLink fabric, delivering massive bisection bandwidth inside the rack.
  • ~30 TB of shared HBM memory
    Expert parameters can be accessed from a rack-wide memory pool without traversing external InfiniBand or Ethernet.
  • Intra-rack expert locality
    Most MoE “expert hops” remain inside the NVLink domain, avoiding the highest-latency communication paths.

This design compresses the MoE critical path, keeping compute units busy instead of waiting on data.

📊 MoE Inference Results: DeepSeek-R1
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Signal65 benchmarks using DeepSeek-R1 (FP4) illustrate the scale of the advantage. At a target of 75 tokens/s per GPU, the GB200 NVL72 running NVIDIA Dynamo achieved 7,707 tokens/s total throughput.

Platform Throughput (tokens/s) Relative
GB200 NVL72 (Dynamo) 7,707 28×
B200 (standard TensorRT) Lower ~4–6×
AMD MI355X (vLLM) Baseline

This delta is structural. Software alone cannot compensate for missing rack-scale coherency and bandwidth.

💰 Performance per Dollar and TCO
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The throughput advantage compounds directly into Total Cost of Ownership (TCO) benefits.

Based on public cloud pricing and measured throughput:

  • Cost per generated token
    GB200 NVL72 is approximately 15× cheaper than MI355X-class deployments in MoE-heavy scenarios.
  • Performance per dollar
    • ~3.1× advantage at 25 tokens/s
    • ~15× advantage at 75 tokens/s

Higher utilization, fewer racks, and lower networking overhead all contribute to the gap.

⚖️ Where MI355X Still Competes
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AMD’s MI355X remains strong for dense models:

  • Large HBM3e capacity benefits monolithic parameter access.
  • Dense inference and training workloads are less sensitive to inter-node latency.

However, AMD currently lacks an equivalent to NVIDIA’s NVLink Switch–based rack fabric, which limits MoE scaling efficiency at high concurrency.

🧭 What This Means for 2026 AI Infrastructure
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The GB200 NVL72 validates a major shift in AI system design:

  • The rack, not the GPU, is the new unit of compute.
  • Interconnect topology is now a first-order performance metric.
  • MoE workloads amplify architectural differences that dense benchmarks hide.

🧩 Conclusion
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In MoE inference, system-level design dominates accelerator specifications. NVIDIA’s Blackwell NVL72 demonstrates that tightly integrated rack-scale architectures can unlock orders-of-magnitude gains that no single GPU upgrade can match. For MoE-driven AI deployment in 2026, the competitive edge belongs to platforms built as systems first, chips second.

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