MiniMax H3 native 1440p on a single RTX 4090 via auto-scheduled sparse attention, open-sourced

This_Temporary_8537 · reddit · 2026-08-30

An indie developer open-sourced X-MinimaxH3, adding an automatically scheduled sparse-attention system for MiniMax H3 that achieves native 720p→1440p second sampling on a single RTX 4090: 112s/223s/334s for 5/10/15-second videos (exploratory runs, not tuned limits).

The core is the scheduler: instead of one fixed sparsity ratio across all denoising steps and layers, it assigns per-location attention budgets along the trajectory, staying conservative around regions critical for motion, consistency and fine detail. Users get a single 0–100 acceleration dial, with 0 as the full Dense reference. The 1440p stage is native H3 latent-space second sampling reusing video/audio latent state — not frame-by-frame upscaling.

The project also ships FL2VA, multi-reference Ref2VA, Base/Turbo LoRA switching, a Web UI, REST API and four ComfyUI workflows; the author seeks feedback from consumer-GPU users (3090/5060/4060).

Related event: Open-Source Project Runs MiniMax H3 on a Single RTX 4090(3 posts)→

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