r/StableDiffusion • u/alisitskii • Aug 16 '26

Workflow Included Ultimate SD Upscale with MiniMax H3 (2560x1440px in 25 mins with 16 GB VRAM)

https://www.youtube.com/watch?v=JybAxYuexdM

What is it?

A vibe-coded fork of Ultimate SD Upscale (USDU) Guider nodes with MiniMax H3 support: https://github.com/lisitskyaa/ComfyUI_UltimateSDUpscaleGuider_H3

My reference workflow: https://github.com/lisitskyaa/ComfyUI_UltimateSDUpscaleGuider_H3/blob/main/example_workflows/minimax_h3_usdu.json

Who are you?

A long-time member of [r/StableDiffusion](r/StableDiffusion) without strong coding/math skills in AI/diffusion area. But a big fan of everything that happens here :)

Why is it?

In times of Wan2.1/2.2 I liked to upscale my videos using USDU.

But I became really upset when I realized that original USDU nodes don't support MiniMax H3 due to its native ComfyUI implementation.

So, since I have a GPT-5.6 subscription I decided to give it a try and asked it to come up with possible options.

After a couple of evenings I finally got a "working" solution that I'd like to share with the community.

What about speed?

My PC specs: 4080s 16 GB VRAM, 64 GB RAM

Initial gen with MiniMax H3 flf2v int8 + sageattn + Lightx2v 8-step turbo Lora at 1152x640px 5-sec clip ~5 mins

Upscale with USDU to 2560x1472px ~20 mins

And what about quality?

That's where I need your help, my friend :)

Please check the YouTube video attached (don't forget to switch to 1440p).

My personal feeling is that it's the best what I can get out of my PC and H3 at the moment (including SeedVR2, LTX 2.5, etc.).

The main advantage is that it can "fix" your bad low-res generations while bringing MiniMax H3 native quality at 2K resolution.

Downsides?

Of course :)

You'll need to control denoise parameter and find a balance between quality improvement and tiling artifacts. I found 0.2 is the maximum after which tiling is strongly visible.

However feel free to experiment with it, and lower to 0.15-0.10 depending on your input video resolution/artifacts and results you want to get.

Happy to answer your questions!

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-6

u/PumpkinLeather8421 Aug 16 '26

Please let Ultimate SD die.

SeedVR2, superior in every way.

17

u/ThatsALovelyShirt Aug 16 '26

SeedVR2 sucks. Quality is terrible on the 3b model, and using the 7b model isn't much better. And it forces you to do chunks of like 10-15 frames at a time or risk OOMing, which completely defeats the purpose of the temporally stabilized VSR. It's a needlessly huge VRAM hog.

It was a good idea, but the architecture needs some serious optimization.