Artificial Intelligence1 min read

When One GPU Isn’t Enough: Serving GLM-5.3 Across Two NVIDIA DGX Stations with vLLM

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In short

Massive artificial intelligence models often surpass the physical memory capacities of individual chips, forcing teams to link multi-system hardware to achieve viable local inference. By coordinating two networked workstations with specialized engines, operators can eliminate slow CPU offloading to handle heavy enterprise workloads directly on high-speed accelerator memory. This distributed approach provides a scalable roadmap for organizations deploying cutting-edge mixture-of-experts architectures within their own infrastructure. In this setup, ConnectX-8 RDMA links two DGX Stations using tensor parallelism to fully accommodate the 464-gigabyte checkpoint on GPU memory.

Key points

  • Connecting two systems via ConnectX-8 RDMA allows model serving entirely without relying…: Connecting two systems via ConnectX-8 RDMA allows model serving entirely without relying on CPU weight offloading.
  • Station A acts as rank 0 to host an OpenAI-compatible API endpoint while Station B operat…: Station A acts as rank 0 to host an OpenAI-compatible API endpoint while Station B operates as a rank 1 worker.
  • Both interconnected stations process every incoming query simultaneously before Station A…: Both interconnected stations process every incoming query simultaneously before Station A returns the final completed answers.

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Running a frontier-scale model locally means keeping all its weights in GPU memory; the largest models no longer fit on one machine. Two NVIDIA DGX Stations connected over ConnectX-8 RDMA serve one model through a single endpoint, with tensor parallelism splitting the model weights and computation across both GPUs.

The NVIDIA GLM-5.3 NVFP4 model, a quantized version of Z.ai’s mixture-of-experts (MoE) model, has 753 billion parameters, with 40 billion activated per token. Sparse activation reduces computation, but all model weights still need to remain available because each token can be routed to different experts. At about 464 GB, the checkpoint exceeds the 252 GB of HBM3e on a single GB300 GPU. This tutorial uses two DGX Stations to keep the weights in GPU memory, with CPU weight offload disabled.

Before starting, connect the two Stations with the Connect Two DGX Stations playbook.

This post shows how to serve GLM-5.3 locally across two NVIDIA DGX Stations with vLLM, send a request, and measure behavior under concurrent load. Tensor parallelism (TP=2) splits the model’s tensors across the two GB300 GPUs. Both Stations…

Artificial Intelligence