Dedicate a GPU to Activation Weights for Higher Res MiniMax H3 Video

yamosin · reddit · 2026-08-21

A user shared a multi-GPU optimization technique for MiniMax H3. By storing UNet weights on cuda:0 and dedicating cuda:1 purely for activations during inference, users gain a full GPU's worth of VRAM for activations with practically zero performance hit.

Test Setup: 3x RTX 3090. Workflow loads CLIP+VAE on cuda:0 and ejects CLIP after conditioning. Half the UNet acts as a storage pool on cuda:0, while the other half serves as the compute device on cuda:1.

Results: Shifting UNet weight distribution (e.g., 3GB vs 16.5GB) resulted in negligible sampling time differences (83s-87s). However, this setup allows significantly higher resolutions and longer video generation within VRAM limits.

Conclusion: Two 16GB cards could potentially handle 0.7MP + 15s videos entirely in VRAM (activations 12GB). This offers massive performance gains compared to system RAM swapping.

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