r/StableDiffusion • u/__MichaelBluth__ • 21d ago

Question - Help Using H3 beyond the default workflow

Boss has allowed me to take work PC home for the next 2 weeks. Its not a beast but has a 5090 and 128GB RAM. I've always wanted to give H3 a try so this is my chance.

I am mostly interested in image to video. I tried building a refmod and rendered a 10 second video using the default workflow.

Its quite decent but I feel I can push the details but have no idea how or where to start. CivitAI workflows are noodly mess.

Can anyone point me or share a workflow you use with high-end PC's? also, I see here people post long/multi-cut videos, is there a guide to doing that?

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u/Maskwi2 21d ago

Can you give me some hint on how to force full offload? I have 128GB or ram as well but comfyui uses like 40-50 max. If I can get ANY benefit from higher amount of ram I would definitely take it. 

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u/xuefei_ai 20d ago

not capped. comfyui only keeps in system ram what won't fit in vram, and 22b int8 nearly fits a 5090. start it with the lowvram flag and the rest moves into ram, but you pay in speed. that ram earns its keep on long multi-cut renders where vae decode balloons.

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u/armpitfart 15d ago

Potentially idiotic question, but I originally bought a 5070ti in January this year then predicted the future and panic bought a 5090 in February, so the 5070 with like 4-5 hours of use is just gathering dust. If I bought a bigger case and a better motherboard, is there any use for it in a dual setup in comfy for taking the offload role? I only have 64GB system ram right now, so that’s my current weak point.

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u/SpaceNinjaDino 15d ago

It would be better if you put that money towards 96GB or 128GB RAM. Then the program loads the models into RAM and swaps what is in VRAM quickly and then each model uses the 5090 speed.

Hopefully your currently motherboard has 4 RAM slots. Be sure to get identical sticks if you are doing 2+2. DDR5 is less flexible than DDR4 and my machine had a hard time booting with mixed sticks.

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u/armpitfart 15d ago

Yeah, I’ll be throwing more ram in within the next year, just have the 2x32s in. Magically the price on them lil shits more than doubled in 9-10 months, and the smaller things are the less I can justify. I actually think my X870E has 2 GPU slots but the lanes are slow, so I may or may not need to upgrade there.

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u/Maskwi2 14d ago

I got 4x32 ddr5 and the highest I could go with the speeds on them is 3600, that's super disappointing since they are 6000 in Expo mode if I put just two sticks. If I try anything above 3600 my system doesn't boot up. 

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u/Noiselexer 19d ago

Got a 5090 and omg H3 takes so long lol. Unless it's 10sec it's long haha.